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Free Fun Math quiz: 60 trivia questions and answers — paradoxes & number puzzles. Easy to hard, with explained answers. No sign-up.
Start this quiz →🖨️ Printable version (20 questions + answers)
You don't need to be good at maths to have fun with numbers! Paradoxes that defy intuition, numerical magic tricks, infinities bigger than others and stories of eccentric geniuses: this quiz shows that mathematics is also about surprise and curiosity.
This quiz currently has 60 questions, ranging from easy to hard, available in French, English and Spanish when the Spanish translation is available.
Warm up before the quiz with these 12 trivia questions and their explained answers: click a question to reveal the answer.
Answer: The googol. The founders wanted to suggest the huge amount of information to be organised. The domain name was reportedly registered with a typo, "google" instead of "googol", and the mistake stuck.
Answer: 14 March. In US notation, 14 March is written 3/14, like 3.14. By coincidence, Albert Einstein was born on 14 March and Stephen Hawking died on 14 March. Some prefer to celebrate on 22 July, because 22/7 ≈ π.
Answer: 1089. Whatever the starting number, as long as it follows the rule, you end up with 1089. It is the basis of an old "mind-reading" trick: the magician has written 1089 in an envelope before you even pick your number.
Answer: A doughnut. In topology, objects can be deformed like modelling clay, without tearing or gluing. A mug and a doughnut both have exactly one hole (the handle and the centre), so they are the "same" object: a torus.
Answer: 45. Each person shakes 9 hands, giving 10 × 9 = 90… but each handshake is then counted twice, once per participant. So there are 90 / 2 = 45. With n people, the formula is n(n − 1)/2.
Answer: 5,050. He reportedly noticed that 1 + 100, 2 + 99, 3 + 98… always make 101, and that there are 50 pairs: 50 × 101 = 5,050. His teacher, who had hoped to keep the class busy for a good while, was disappointed.
Answer: About 18 billion billion. The total is 2⁶⁴ − 1, or 18,446,744,073,709,551,615 grains. That is hundreds of billions of tonnes: nearly a thousand years of world rice production. The king supposedly grasped the power of exponentials a little too late.
Answer: More than 100 trillion. Since 2022, records have been counted in hundreds of trillions of digits. Printed out, they would fill millions of books. They have no practical use, but these calculations are used to test computers and algorithms.
Answer: 6174. This is Kaprekar's constant, discovered by an Indian mathematician in 1949. Example: 3524 → 5432 − 2345 = 3087 → 8730 − 0378 = 8352 → 8532 − 2358 = 6174, which then gives 6174 for ever. It takes at most seven steps.
Answer: By asking every guest to move from room n to room n + 1. Every guest moves along one room, and room 1 becomes free. The mathematician David Hilbert imagined this hotel to show that infinity does not behave like large numbers: it can even take in infinitely many new guests!
Answer: 9. From each of the 6 vertices you can draw 3 diagonals to non-adjacent vertices, giving 6 × 3 = 18, divided by 2 because each diagonal is counted twice: 9. The general formula for an n-sided polygon is n(n − 3)/2.
Answer: He turned it down. Perelman had already refused the Fields Medal in 2006, saying he did not want to be displayed "like an animal in a zoo". In 2010 he also declined the Clay Institute's Millennium Prize, feeling that others deserved it as much as he did.
48 more questions are waiting for you in the quiz!