Math & Numbers Facts for Kids
Mind-bending number facts
Online banking and secure websites rely on extremely large prime numbers. Multiplying two big primes together is easy, but working out which two primes were used is practically impossible for a computer β and that is what keeps your data safe.
Zero is special because it is neither positive nor negative. It sits right in the middle of the number line.
The Collatz conjecture is one of the simplest unsolved problems in mathematics: pick any number, if it is even halve it, if it is odd multiply by 3 and add 1, and repeat. Nobody has proved that this always reaches 1.
A circle has an infinite number of lines of symmetry β you can fold it in half along any line through its centre and both halves match perfectly.
In the early 1600s, Scottish mathematician John Napier invented a set of numbered rods called 'Napier's bones' that made multiplication and division much faster β a kind of early calculator.
A million seconds is about 11.5 days, but a billion seconds is roughly 31.7 years. That shows just how much bigger a billion is than a million!
Mathematicians proved that any flat map can be coloured using just four colours so that no two neighbouring regions share the same colour. It took over a century to prove!
In 1994, a group of Inupiaq students in Kaktovik, Alaska, invented a new numeral system that works perfectly with their base-20 counting tradition. The Kaktovik numerals are now taught in some Alaskan schools.
Triangular numbers (1, 3, 6, 10, 15, 21...) are called that because you can arrange that many dots into a perfect triangle. Bowling pins are set up as the triangular number 10!
Graham's number is so enormous that even if every digit were written in the tiniest possible font, the observable universe would not be large enough to contain it.