6 is called a perfect number. Why?Answer: Its smaller divisors 1, 2 and 3 add up to 6. Source: Wikipedia: Perfect number
6 is the first perfect number. What is the next one?Answer: 28. Source: Wikipedia: Perfect number
A googolplex is a 1 followed by how many zeros?Answer: A googol of zeros. Source: Wikipedia: Googolplex
A gross is a dozen dozens. How many is that?Answer: 144. Source: Wikipedia: Gross (unit)
A number such as 16361 reads the same forward and backward. What is a number like that called?Answer: A palindromic number. Source: Wikipedia: Palindromic number
A score is an old word for a group of how many?Answer: Twenty. Source: Wikipedia: 20 (number)
An abacus is a calculating tool that has been used since ancient times. What do you slide on it?Answer: Beads. Source: Wikipedia: Abacus
The ancient Sumerians and Babylonians counted in sixties. Where is their base 60 still used today?Answer: In measuring time and angles. Source: Wikipedia: Sexagesimal
Computers work with binary numbers. How many different digits does binary use?Answer: Two. Source: Wikipedia: Binary number
The Fibonacci sequence begins 1, 1, 2, 3, 5, 8, 13. How do you get the next number?Answer: Add the two numbers before it. Source: Wikipedia: Fibonacci sequence
In a book of 1202, Fibonacci used his famous sequence to count a growing family of which animals?Answer: Rabbits. Source: Wikipedia: Fibonacci sequence
In ancient Greek counting, how many was a myriad?Answer: Ten thousand. Source: Wikipedia: Myriad
In computing, the word 'bit' is short for what?Answer: Binary digit. Source: Wikipedia: Binary number
In his book Elements, Euclid proved something about prime numbers. What was it?Answer: There are infinitely many of them. Source: Wikipedia: Euclid's theorem
Is zero an even number or an odd number?Answer: Even. Source: Wikipedia: Parity (mathematics)
The Ishango bone is a carved bone that may be a very early math tool. In which country was it found?Answer: The Democratic Republic of the Congo. Source: Wikipedia: Ishango bone
Maya numerals used a dot for one and a bar for five. What stood for zero?Answer: A shell. Source: Wikipedia: Maya numerals
Napier's bones were a set of rods made by John Napier of Scotland in 1617. What were they for?Answer: Multiplying and dividing numbers. Source: Wikipedia: Napier's bones
The number pi is about 3.14. What does it compare?Answer: The distance around a circle with the distance across it. Source: Wikipedia: Pi
The number system we use today, with ten digits and place value, was invented by mathematicians of which land?Answer: India. Source: Wikipedia: Hindu–Arabic numeral system
Numbers such as 4, 9 and 16 are called square numbers. What can you do with that many dots?Answer: Arrange them in rows to make a square. Source: Wikipedia: Square number
The oldest known tally sticks are notched bones. About how old are they?Answer: 25,000 to 35,000 years. Source: Wikipedia: Tally marks
Pi Day is kept on March 14. Why that date?Answer: Month 3, day 14 matches 3.14. Source: Wikipedia: Pi Day
The Rhind Papyrus is a famous old scroll of math problems. Which ancient people wrote it?Answer: The Egyptians. Source: Wikipedia: Rhind Mathematical Papyrus
Roman numerals have no symbol for which number?Answer: Zero. Source: Wikipedia: Roman numerals
The soroban is a kind of abacus with one bead above and four below on each rod. Which country is it from?Answer: Japan. Source: Wikipedia: Soroban
Tally marks are usually bundled in groups of how many?Answer: Five. Source: Wikipedia: Tally marks
We count in tens. The ancient Maya counted in groups of how many?Answer: Twenty. Source: Wikipedia: Maya numerals
What do we call numbers that are less than zero?Answer: Negative numbers. Source: Wikipedia: Negative number
What is a googol?Answer: A 1 with one hundred zeros after it. Source: Wikipedia: Googol
What is special about the digits of pi after the decimal point?Answer: They never end and never settle into a repeating pattern. Source: Wikipedia: Pi
What is the sieve of Eratosthenes used to find?Answer: Prime numbers. Source: Wikipedia: Sieve of Eratosthenes
Where are you most likely to see Roman numerals still in use today?Answer: On a clock face. Source: Wikipedia: Roman numerals
Which Indian mathematician, who wrote a great work dated 628, is credited as the first to treat zero as a number?Answer: Brahmagupta. Source: Wikipedia: Brahmagupta
Who came up with the word 'googol' in 1920?Answer: A nine-year-old boy. Source: Wikipedia: Googol
The word 'zero' goes back to the Arabic word 'sifr'. What did 'sifr' first mean?Answer: Empty. Source: Wikipedia: 0
Famous mathematicians 38
A story says that Thales found the height of the pyramids of Egypt without climbing them. What did he measure?Answer: Their shadows. Source: Wikipedia: Thales of Miletus
A story says that young Carl Friedrich Gauss amazed his teacher by quickly adding all the numbers from 1 to 100. What is the total?Answer: 5,050. Source: Wikipedia: Carl Friedrich Gauss
Ada Lovelace wrote about an early design for a computer. Her father was which famous English poet?Answer: Lord Byron. Source: Wikipedia: Ada Lovelace
After earning her doctorate in 1907, the great mathematician Emmy Noether worked at an institute for seven years without what?Answer: Pay. Source: Wikipedia: Emmy Noether
Archimedes asked for two shapes to be placed on his tomb, to stand for his favorite discovery. Which two?Answer: A sphere and a cylinder. Source: Wikipedia: Archimedes
Archimedes came from the ancient city of Syracuse. On which island is Syracuse?Answer: Sicily. Source: Wikipedia: Archimedes
Around 1753, Benjamin Banneker reportedly built a clock that struck the hour, copied from a borrowed pocket watch. What was it made of?Answer: Wood. Source: Wikipedia: Benjamin Banneker
Babbage's analytical engine was to take in its programs on punched cards. Which machines of the time were already run by such cards?Answer: Weaving looms. Source: Wikipedia: Analytical engine
Blaise Pascal was 18 when, in 1642, he began to build a mechanical calculator. Whose work was it meant to make lighter?Answer: His father's, who worked on taxes. Source: Wikipedia: Pascaline
The Cartesian coordinate system, which locates a point with an x and a y, is named after which French thinker?Answer: René Descartes. Source: Wikipedia: René Descartes
Charles Babbage, called by some the 'father of the computer', gets the credit for the first mechanical computer. What was it called?Answer: The difference engine. Source: Wikipedia: Charles Babbage
During World War II, the mathematician Alan Turing worked at Bletchley Park in England. What was done there?Answer: Secret codes were broken. Source: Wikipedia: Alan Turing
Eratosthenes was the Library of Alexandria's chief librarian. He is remembered above all as the first person known to work out what?Answer: The distance around the Earth. Source: Wikipedia: Eratosthenes
Euclid's Elements has been used to teach geometry for over 2,000 years. It is often called the most successful what ever written?Answer: Textbook. Source: Wikipedia: Euclid's Elements
Euclid's great work, the Elements, is a collection of how many books?Answer: 13. Source: Wikipedia: Euclid's Elements
Fibonacci's book Liber Abaci, written in 1202, is famous for bringing what to Europe?Answer: The numerals we use today. Source: Wikipedia: Liber Abaci
Florence Nightingale is famous as a nurse. What was she also a pioneer of?Answer: Showing statistics as charts. Source: Wikipedia: Florence Nightingale
G. H. Hardy once told Srinivasa Ramanujan that 1729 seemed a rather dull number. Where had Hardy just seen it?Answer: On the taxi cab he rode in. Source: Wikipedia: Srinivasa Ramanujan
Georg Cantor proved something surprising about infinity. What was it?Answer: Some infinite sets are bigger than others. Source: Wikipedia: Georg Cantor
Gottfried Leibniz is credited with devising the modern form of which number system, now the basis of digital computing?Answer: Binary. Source: Wikipedia: Gottfried Wilhelm Leibniz
Hypatia is the first woman mathematician with a life fairly well recorded. In which city did she live and teach?Answer: Alexandria. Source: Wikipedia: Hypatia
In 2014 Maryam Mirzakhani became the first woman to win which top prize in mathematics?Answer: The Fields Medal. Source: Wikipedia: Maryam Mirzakhani
In a famous story, a king asked Euclid for a quicker way to learn geometry. What did Euclid say there was none of?Answer: A royal road to geometry. Source: Wikipedia: Euclid
Isaac Newton shares the credit for creating calculus with which German mathematician?Answer: Gottfried Wilhelm Leibniz. Source: Wikipedia: Isaac Newton
John Napier of Scotland is best known for discovering logarithms. Which small mark did he also help to make popular in arithmetic?Answer: The decimal point. Source: Wikipedia: John Napier
John Venn is known for his diagrams. With his son, he also built a machine that could bowl a spinning ball in which sport?Answer: Cricket. Source: Wikipedia: John Venn
Leonhard Euler wrote 866 works and is called perhaps the most prolific mathematician in history. Which country was he from?Answer: Switzerland. Source: Wikipedia: Leonhard Euler
The name Fibonacci is short for the Latin 'filius Bonacci'. What does that mean?Answer: Son of Bonacci. Source: Wikipedia: Fibonacci
On which Greek island was Pythagoras born?Answer: Samos. Source: Wikipedia: Pythagoras
Pierre de Fermat is one of the great names of mathematics, but it was not his day job. What was his profession?Answer: The law. Source: Wikipedia: Pierre de Fermat
The Pythagorean theorem is a famous rule about the sides of which shape?Answer: A right triangle. Source: Wikipedia: Pythagorean theorem
Sophie Germain, a French mathematician born in 1776, wrote to famous mathematicians under a made-up name. What was it?Answer: Monsieur Le Blanc. Source: Wikipedia: Sophie Germain
When NASA first used electronic computers to work out an astronaut's orbit, which mathematician was asked to check the numbers?Answer: Katherine Johnson. Source: Wikipedia: Katherine Johnson
Which ancient Greek mathematician is known as the 'father of geometry'?Answer: Euclid. Source: Wikipedia: Euclid
Which German mathematician has been called the 'Prince of Mathematics'?Answer: Carl Friedrich Gauss. Source: Wikipedia: Carl Friedrich Gauss
Which of these did the Scottish engineer William Playfair invent?Answer: The bar chart and the pie chart. Source: Wikipedia: William Playfair
The word 'algebra' comes from 'Al-Jabr', the short title of a book by al-Khwarizmi. In which language did he write?Answer: Arabic. Source: Wikipedia: Al-Khwarizmi
The word 'algorithm' comes from the name of a mathematician who worked in Baghdad around 820. Who was he?Answer: Al-Khwarizmi. Source: Wikipedia: Al-Khwarizmi
Shapes in nature and around you 24
A coil spring and the thread of a screw share the same twisting shape, which is also found in DNA. What is it called?Answer: A helix. Source: Wikipedia: Helix
A cube has 6 faces. How many edges does it have?Answer: 12. Source: Wikipedia: Cube
A legend says that the stone columns of the Giant's Causeway are the remains of a path across the sea. Who built it in the story?Answer: An Irish giant. Source: Wikipedia: Giant's Causeway
A Platonic solid has faces that are all the same regular shape, such as a cube with its six squares. How many Platonic solids are there?Answer: Five. Source: Wikipedia: Platonic solid
A regular icosahedron is one of the five Platonic solids, which are often used to make fair dice. What shape is each of its twenty faces?Answer: A triangle. Source: Wikipedia: Platonic solid
A shape has rotational symmetry when it does what?Answer: Looks the same after part of a turn. Source: Wikipedia: Rotational symmetry
A tetrahedron is the simplest solid shape with flat faces. How many faces does it have?Answer: Four. Source: Wikipedia: Tetrahedron
The classic soccer ball is stitched from white and black panels. Which two shapes are they?Answer: Hexagons and pentagons. Source: Wikipedia: Truncated icosahedron
Fibonacci numbers turn up in living things. In which of these can you find them?Answer: The scales of a pine cone. Source: Wikipedia: Fibonacci sequence
The Giant's Causeway in Northern Ireland is made of about 40,000 stone columns. What shape are most of their tops?Answer: Hexagons. Source: Wikipedia: Giant's Causeway
The Great Pyramid of Giza was the tallest structure made by people for a very long time. For about how long?Answer: More than 3,700 years. Source: Wikipedia: Great Pyramid of Giza
Honey bees build the wax cells of a honeycomb in which shape?Answer: Hexagons. Source: Wikipedia: Hexagon
In a circle, what do we call the distance from the center to the edge?Answer: The radius. Source: Wikipedia: Circle
The mathematician Jacob Bernoulli loved the logarithmic spiral so much that he gave it a Latin name. What does 'spira mirabilis' mean?Answer: The marvelous spiral. Source: Wikipedia: Logarithmic spiral
Only three regular shapes can tile a floor by themselves with no gaps. Two are the square and the equal-sided triangle. What is the third?Answer: The regular hexagon. Source: Wikipedia: Tessellation
The path of each planet around the Sun is close to which shape?Answer: An ellipse. Source: Wikipedia: Ellipse
The point at the very top of a pyramid or a cone has a special name. What is it?Answer: The apex. Source: Wikipedia: Pyramid (geometry)
Romanesco broccoli is made of buds that are made of smaller buds of the same shape, again and again. What is a shape like that called?Answer: A fractal. Source: Wikipedia: Romanesco broccoli
The shell of the nautilus, a sea animal, is one of nature's finest examples of which curve?Answer: A logarithmic spiral. Source: Wikipedia: Nautilus
What is a tessellation?Answer: A pattern of tiles with no gaps and no overlaps. Source: Wikipedia: Tessellation
Which shape does a soap bubble floating in the air take?Answer: A sphere. Source: Wikipedia: Soap bubble
The word 'fractal' was coined in 1975 from the Latin 'fractus'. What does 'fractus' mean?Answer: Broken. Source: Wikipedia: Fractal
The word hexagon comes from two Greek words. 'Gonia' means corner or angle. What does 'hex' mean?Answer: Six. Source: Wikipedia: Hexagon
The word polygon comes from Greek. What does it mean?Answer: Having many angles. Source: Wikipedia: Polygon
Famous puzzles and problems 19
1729 is called the Ramanujan number. What is special about it?Answer: It is two cubes added together, in two separate ways. Source: Wikipedia: 1729 (number)
A tangram is a puzzle of flat pieces that you arrange to make pictures. How many pieces does it have?Answer: Seven. Source: Wikipedia: Tangram
Around 1637, Pierre de Fermat wrote down a famous theorem in the margin of a book. What did he say about his proof?Answer: It was too large to fit in the margin. Source: Wikipedia: Fermat's Last Theorem
The four color theorem was the first major theorem proved with the help of what?Answer: A computer. Source: Wikipedia: Four color theorem
Goldbach's conjecture is a famous unsolved problem. It says that every even number above 2 is the sum of two what?Answer: Prime numbers. Source: Wikipedia: Goldbach's conjecture
How do you make a Möbius strip from a strip of paper?Answer: Give it a half-twist and join the ends. Source: Wikipedia: Möbius strip
How many colors are enough to color any flat map so that no two neighboring regions match?Answer: Four. Source: Wikipedia: Four color theorem
In a classic Sudoku, which digits must appear in every row, every column and every box?Answer: 1 to 9. Source: Wikipedia: Sudoku
In a magic square, what is true of every row, every column and both main diagonals?Answer: They come to the same sum. Source: Wikipedia: Magic square
In an old story, grains of wheat are put on a chessboard: 1 on the first square, 2 on the next, then 4. What is the rule?Answer: Each square gets double the one before. Source: Wikipedia: Wheat and chessboard problem
In Pascal's triangle, how do you work out each new number?Answer: Add the two numbers above it. Source: Wikipedia: Pascal's triangle
In the Chinese legend of the Lo Shu magic square, which animal carried the pattern of dots on its shell?Answer: A turtle. Source: Wikipedia: Luoshu Square
In the Tower of Hanoi puzzle you move a stack of disks between three rods. What is the smallest number of moves for three disks?Answer: Seven. Source: Wikipedia: Tower of Hanoi
The Lo Shu is an ancient Chinese magic square that uses the numbers 1 to 9. What does every line in it add up to?Answer: 15. Source: Wikipedia: Luoshu Square
The name of the puzzle Sudoku is Japanese. What does it mean?Answer: Single number. Source: Wikipedia: Sudoku
The old puzzle of the Seven Bridges of Königsberg asked for a walk crossing each bridge exactly once. What did Euler prove in 1736?Answer: That it cannot be done. Source: Wikipedia: Seven Bridges of Königsberg
The Romans called a coin toss 'ship or head'. Why?Answer: Certain coins showed a ship on one face and the emperor's head on the other. Source: Wikipedia: Coin flipping
What do you get if you cut a Möbius strip all the way along its center line?Answer: One long strip. Source: Wikipedia: Möbius strip
What makes two prime numbers, such as 11 and 13, a pair of twin primes?Answer: They are just 2 apart. Source: Wikipedia: Twin prime
Measuring and time 29
A fortnight is an old word for a length of time. How long is it?Answer: 14 days. Source: Wikipedia: Fortnight
A furlong is one-eighth of a mile. In which sport is it still used to measure distances?Answer: Horse racing. Source: Wikipedia: Furlong
A sundial tells the time with a shadow. What is the part that casts the shadow called?Answer: The gnomon. Source: Wikipedia: Sundial
About how many weeks are in one year?Answer: 52. Source: Wikipedia: Week
An hourglass has two glass bulbs joined by a narrow neck. What usually flows from the top bulb to the bottom one?Answer: Sand. Source: Wikipedia: Hourglass
Century is from the Latin word 'centum'. What does centum mean?Answer: One hundred. Source: Wikipedia: Century
The cubit was an ancient unit of length. Which part of the body was it based on?Answer: The arm, from elbow to fingertip. Source: Wikipedia: Cubit
December's name comes from 'decem', the Latin for ten. Why was it the tenth month in the oldest Roman calendar?Answer: The year began in March. Source: Wikipedia: December
How long is a millennium?Answer: 1,000 years. Source: Wikipedia: Millennium
How many inches are in one yard?Answer: 36. Source: Wikipedia: Yard
How many seconds are in one hour?Answer: 3,600. Source: Wikipedia: Hour
In the metric system, what does the prefix 'milli' do to a unit?Answer: Divides it by one thousand. Source: Wikipedia: Metric prefix
In the Middle Ages, an acre was the land one man could plough in a day with a team of which animals?Answer: Eight oxen. Source: Wikipedia: Acre
The Julian calendar added a leap day every fourth year. Which Roman leader is it named after?Answer: Julius Caesar. Source: Wikipedia: Julian calendar
The letters a.m. come from the Latin words 'ante meridiem'. What do they mean?Answer: Before midday. Source: Wikipedia: 12-hour clock
The metric prefix 'kilo' comes from a Greek word. What does the word mean?Answer: Thousand. Source: Wikipedia: Kilo-
The mile gets its name from the Roman mile. How did the Romans count out their mile?Answer: One thousand paces. Source: Wikipedia: Mile
October is the tenth month, but its name comes from the Latin for which number?Answer: Eight. Source: Wikipedia: October
The oldest Roman calendar had ten months. Which two months were added to it later?Answer: January and February. Source: Wikipedia: Roman calendar
On a 24-hour clock, what time is shown one minute before midnight?Answer: 23:59. Source: Wikipedia: 24-hour clock
Paper is sold by the ream. How many sheets are in a ream?Answer: 500. Source: Wikipedia: Units of paper quantity
Ships and aircraft measure speed in knots. One knot is one of which unit per hour?Answer: Nautical mile. Source: Wikipedia: Knot (unit)
The symbol for the pound is lb. Which Roman unit of weight does it come from?Answer: The libra. Source: Wikipedia: Pound (mass)
When the Gregorian calendar began in October 1582, how many days were skipped?Answer: 10. Source: Wikipedia: Gregorian calendar
When the meter was first defined in 1791, it was one ten-millionth of which distance?Answer: From the equator up to the North Pole. Source: Wikipedia: Metre
The word 'minute' comes from a Latin phrase. What does the phrase mean?Answer: First small part. Source: Wikipedia: Minute
The word clock comes from a medieval Latin word, 'clocca'. What does clocca mean?Answer: Bell. Source: Wikipedia: Clock
The word furlong comes from two Old English words. What did a furlong first measure?Answer: The length of a furrow in a ploughed field. Source: Wikipedia: Furlong
The word inch comes from the Roman word 'uncia'. What does uncia mean?Answer: Twelfth. Source: Wikipedia: Inch
Math words and symbols 30
A mathematician who works in geometry has a special name. What is it?Answer: A geometer. Source: Wikipedia: Geometry
A Venn diagram shows how sets of things overlap. Which shapes is it usually drawn with?Answer: Overlapping circles. Source: Wikipedia: Venn diagram
The earliest known use of the × sign for multiplication is in a book printed in which year?Answer: 1618. Source: Wikipedia: Multiplication sign
How many times longer is the diameter of a circle than its radius?Answer: Two times. Source: Wikipedia: Diameter
In a pie chart, what does the size of each slice show?Answer: How big a share of the whole it stands for. Source: Wikipedia: Pie chart
In a set of numbers, what do we call the value that appears most often?Answer: The mode. Source: Wikipedia: Mode (statistics)
In British English, a four-sided shape with a pair of parallel sides is a trapezium. What is it called in North American English?Answer: A trapezoid. Source: Wikipedia: Trapezoid
In geometry, what is the drawing tool called a compass used to draw?Answer: Circles and arcs. Source: Wikipedia: Compass (drawing tool)
In Latin, the word 'calculus' means a small thing that the Romans used as a counter. What is it?Answer: A pebble. Source: Wikipedia: Calculus
In math, 5 × 5 is called '5 squared'. Why 'squared'?Answer: It is a square's area when it has sides of 5. Source: Wikipedia: Exponentiation
In the way most English speakers count today, how many millions make one billion?Answer: One thousand. Source: Wikipedia: Billion
The infinity symbol looks like a figure 8 lying on its side. Which nickname does it have?Answer: Lazy eight. Source: Wikipedia: Infinity symbol
Obelus, the old name for the ÷ sign, comes from an Ancient Greek word. What did that word mean?Answer: A sharpened stick. Source: Wikipedia: Obelus
The perimeter of a circle has a special name. What is it?Answer: The circumference. Source: Wikipedia: Perimeter
Robert Recorde called the two lines of his equals sign 'Gemowe lines'. What does gemowe mean?Answer: Twin. Source: Wikipedia: Equals sign
The sign ÷ was first used for division in an algebra book of 1659. What is the old name of the sign?Answer: The obelus. Source: Wikipedia: Division sign
What does the word 'percent' mean?Answer: By the hundred. Source: Wikipedia: Percentage
What is the longest side of a right triangle called?Answer: The hypotenuse. Source: Wikipedia: Hypotenuse
When a set of numbers is put in order, what do we call the value in the middle?Answer: The median. Source: Wikipedia: Median
When you divide one number by another, what is the answer called?Answer: The quotient. Source: Wikipedia: Quotient
Which branch of math deals with adding, subtracting, multiplying and dividing?Answer: Arithmetic. Source: Wikipedia: Arithmetic
Which sign did the Welsh mathematician Robert Recorde invent in 1557?Answer: The equals sign. Source: Wikipedia: Robert Recorde
Who first used the infinity symbol in mathematics, in the 17th century?Answer: John Wallis. Source: Wikipedia: Infinity symbol
The word 'digit' comes from the Latin word 'digiti'. What does digiti mean?Answer: Fingers. Source: Wikipedia: Numerical digit
The word 'hypotenuse' comes from a Greek word. What does that word mean?Answer: Stretching under. Source: Wikipedia: Hypotenuse
The word 'million' is built on the Italian word 'mille'. What does mille mean?Answer: Thousand. Source: Wikipedia: 1,000,000
The word parallelogram comes from Greek. What does it mean?Answer: A shape of parallel lines. Source: Wikipedia: Parallelogram
The word quadrilateral comes from two Latin words. 'Quadri' means four. What does 'latus' mean?Answer: Side. Source: Wikipedia: Quadrilateral
The words plus and minus come from Latin. What do they mean?Answer: More and less. Source: Wikipedia: Plus and minus signs
You add up a set of numbers, then divide by how many numbers there are. What have you found?Answer: The mean. Source: Wikipedia: Arithmetic mean
Number riddles 33
A chessboard is 8 squares by 8. Counting squares of every size, from 1 by 1 up to 8 by 8, how many squares can you find on it?Answer: 204. Source: Own work: checked by working it
A clock chimes once at 1 o'clock, twice at 2 o'clock, and so on. How many chimes is that from 1 o'clock through 12 o'clock?Answer: 78. Source: Own work: checked by working it
A farm has hens and cows. Together they have 10 heads and 28 legs. How many cows are there?Answer: 4. Source: Own work: checked by working it
A mother is 30 and her son is 6. In how many years will she be exactly three times as old as he is?Answer: 6 years. Source: Own work: checked by working it
A pencil and an eraser cost $1.10 together. The pencil costs exactly $1 more than the eraser. How much is the eraser?Answer: 5 cents. Source: Own work: checked by working it
A snail climbs a 10-foot wall. Each day it goes up 3 feet, and each night it slips back 2 feet. On which day does it reach the top?Answer: Day 8. Source: Own work: checked by working it
Add me to myself or multiply me by myself, and you get the same answer. I am not zero. What number am I?Answer: 2. Source: Own work: checked by working it
Apart from 1, which is the only number under 100 that is both a square number and a cube number?Answer: 64. Source: Own work: checked by working it
Five friends meet, and each one shakes hands once with every other friend. How many handshakes are there?Answer: 10. Source: Own work: checked by working it
How many minutes are there in one whole day?Answer: 1,440. Source: Own work: checked by working it
How many odd numbers are there from 1 to 99?Answer: 50. Source: Own work: checked by working it
How many two-digit whole numbers are there?Answer: 90. Source: Own work: checked by working it
I am a number. Double me, then add 6, and you get 20. What number am I?Answer: 7. Source: Own work: checked by working it
I am a two-digit number. My two digits are the same, and they add up to 12. What number am I?Answer: 66. Source: Own work: checked by working it
I am an odd number. Take away my first letter and I become even. What number am I?Answer: Seven. Source: Own work: checked by working it
I am less than 50. Divide me by 2, by 3 or by 5 and there is always 1 left over. I am not 1. What number am I?Answer: 31. Source: Own work: checked by working it
If you write out every whole number from 1 to 100, how many times do you write the digit 9?Answer: 20. Source: Own work: checked by working it
If you write out the whole numbers from 1 to 20, how many digits do you write altogether?Answer: 31. Source: Own work: checked by working it
In a race, you overtake the runner who is in second place. Which place are you in now?Answer: Second. Source: Own work: checked by working it
In the list 1, 3, 6, 10, 15, each jump is one bigger than the jump before. What number comes next?Answer: 21. Source: Own work: checked by working it
Multiply together all the whole numbers from 1 to 5. What do you get?Answer: 120. Source: Own work: checked by working it
My three digits are 1, 2 and 3 in some order. I am an even number, and I am bigger than 200. What number am I?Answer: 312. Source: Own work: checked by working it
These are the first five square numbers: 1, 4, 9, 16, 25. What is the next one?Answer: 36. Source: Own work: checked by working it
Today is Monday. What day of the week will it be 100 days from now?Answer: Wednesday. Source: Own work: checked by working it
Two whole numbers add up to 10 and multiply to make 24. What are they?Answer: 4 and 6. Source: Own work: checked by working it
What do you get when you add up all the whole numbers from 1 to 10?Answer: 55. Source: Own work: checked by working it
What is half of a quarter of 80?Answer: 10. Source: Own work: checked by working it
What is the biggest number you can make with the digits 3, 8 and 5, using each digit once?Answer: 853. Source: Own work: checked by working it
What is the smallest number that 1, 2, 3, 4, 5 and 6 all divide into with nothing left over?Answer: 60. Source: Own work: checked by working it
Which of these number words has all its letters in alphabetical order?Answer: Forty. Source: Own work: checked by working it
Which of these number words has exactly as many letters as the number it names?Answer: Four. Source: Own work: checked by working it
Which whole number, multiplied by itself, makes 169?Answer: 13. Source: Own work: checked by working it
You fold a sheet of paper in half, then in half again, 5 folds in all. How many layers thick is it now?Answer: 32. Source: Own work: checked by working it
5th grade challenge 25
A box is 4 units long, 3 units wide and 2 units high. How many unit cubes does it take to fill it?Answer: 24. Source: Own work: checked by working it
A meter is 100 centimeters. How many centimeters are in 2.5 meters?Answer: 250. Source: Own work: checked by working it
A parallelogram that has four right angles has a more common name. What is it?Answer: A rectangle. Source: Wikipedia: Parallelogram
In the number 4.375, which digit is in the hundredths place?Answer: 7. Source: Own work: checked by working it
In the number 770, the first 7 is worth how many times as much as the second 7?Answer: 10 times. Source: Own work: checked by working it
Look at the decimals 0.4, 0.35, 0.309 and 0.04. Which one is the largest?Answer: 0.4. Source: Own work: checked by working it
On a coordinate grid you start at the point (2, 3) and move 4 units to the right. Where are you now?Answer: (6, 3). Source: Own work: checked by working it
On a coordinate grid, the first axis runs left to right. Which way does the second axis usually run?Answer: Up and down. Source: Wikipedia: Cartesian coordinate system
On a coordinate grid, what is the point where the two axes cross called?Answer: The origin. Source: Wikipedia: Origin (mathematics)
One list starts at 0 and adds 2 each time. Another starts at 0 and adds 8 each time. How do the matching numbers compare?Answer: The second is always 4 times the first. Source: Own work: checked by working it
PEMDAS helps students recall which operations come first. What does the P stand for?Answer: Parentheses. Source: Wikipedia: Order of operations
Three pizzas are shared equally among 4 friends. How much pizza does each friend get?Answer: 3/4 of a pizza. Source: Own work: checked by working it
The two axes of a coordinate grid divide the flat plane into four parts. What are the parts called?Answer: Quadrants. Source: Wikipedia: Cartesian coordinate system
What is 0.5 written as a fraction in its simplest form?Answer: 1/2. Source: Own work: checked by working it
What is 1/2 + 1/3?Answer: 5/6. Source: Own work: checked by working it
What is 1/2 × 1/4?Answer: 1/8. Source: Own work: checked by working it
What is 2 × (3 + 4)?Answer: 14. Source: Own work: checked by working it
What is 3.2 + 1.85?Answer: 5.05. Source: Own work: checked by working it
What is 3.86 rounded to the nearest tenth?Answer: 3.9. Source: Own work: checked by working it
What is 3/4 of 20?Answer: 15. Source: Own work: checked by working it
What is 4 ÷ 1/2?Answer: 8. Source: Own work: checked by working it
What is 25 × 12?Answer: 300. Source: Own work: checked by working it
When 10 to the power of 6 is written out in full, how many zeros does it have?Answer: 6. Source: Own work: checked by working it
Which expression means 'add 9 and 5, then multiply by 3'?Answer: 3 × (9 + 5). Source: Own work: checked by working it
Which measurement tells you how much three-dimensional space a box takes up?Answer: Its volume. Source: Wikipedia: Volume
How it works
Most of these 234 math trivia questions for kids are facts, not sums. What is a googol? Which shape do honey bees build in? What did Euclid tell the king who wanted a shortcut? They suit ages 8 to 12 and come in eight topics.
Read the full guide
Eight topics, from tally bones to a taxi cab
Numbers old and new runs from tally bones to the Maya counting in twenties. Famous mathematicians is the hardest. Only one of its 38 questions is easy. The rest ask about Hypatia's city or the number on Hardy's taxi cab. Measuring and time and Math words and symbols open gently, with nine easy questions each.
A 5th grade topic and riddles that need a pencil
5th grade challenge holds 25 math trivia questions for 5th graders. It follows the grade 5 Common Core areas: parentheses, place value and decimals, fractions, volume, the coordinate plane and sorting shapes. Number riddles has 33 puzzles, such as how many squares of every size are on a chessboard. Pick either under Start from, below the question, play a set, then press Print to put them on paper.
Hand out scrap paper for Number riddles: the snail on the wall and the pencil and eraser each have a tempting wrong answer.
Start a mixed-age group on Measuring and time: how long a fortnight is, and which number October is named for.
Read the reason aloud in Famous mathematicians. Stories, such as why Hardy called 1729 a dull number, are what children repeat.
Questions and answers
What ages are these questions for?
Ages 8 to 12. An eight-year-old can say how many tally marks make a bundle. A twelve-year-old may not know what 'sifr', the root of zero, first meant. About a third are hard, by our estimate, and Famous mathematicians holds 20 of them.
Is this a page of sums to practice?
No. Of the 234 questions, 182 are facts about numbers, shapes, measures, math words and famous puzzles. The other 52 need working out: 33 riddles and 19 sums in the 5th grade topic. It suits a quiz round or a lesson warm-up, not times-table drill.
How were the riddles and sums checked?
They were worked by hand, and a short program confirmed no other choice fits. The 182 facts were read on September 19, 2026 in the Wikipedia articles linked under them. Records that change, such as the largest known prime, are out.