Math & Numbers Facts for Kids
Mind-bending number facts
The number 1 is not a prime number. Mathematicians decided this because including 1 as prime would break important rules about how numbers multiply together, such as the unique prime factorisation rule.
Fractals are shapes that look the same no matter how much you zoom in on them. The coastline of Britain is famously fractal-like β the more precisely you measure it, the longer it appears to be.
The nine times table has a handy trick: hold out all ten fingers, fold down the nth finger for 9 Γ n, and count fingers left and right of the fold to get the answer. For 9 Γ 7, fold the 7th finger: 6 fingers left and 3 right = 63.
The golden ratio, approximately 1.618, appears in art, architecture, and nature. Ancient Greek architects used it in the Parthenon, and it appears in the spiral of a sunflower.
In mathematics, infinity plus one is still infinity. Georg Cantor showed in the 1800s that there are actually different sizes of infinity, with some infinities bigger than others.
If you walk around any convex polygon and measure every exterior angle, they always add up to exactly 360 degrees, no matter how many sides the polygon has.
Ancient Babylonians used a base-60 number system, which is why we still divide an hour into 60 minutes and a minute into 60 seconds today.
A Pythagorean triple is a set of three whole numbers that fit the equation aΒ² + bΒ² = cΒ². The simplest is 3, 4, 5 β because 9 + 16 = 25.
Sudoku puzzles are based on a mathematical idea called a Latin square, where each number appears exactly once in every row and column. Mathematician Leonhard Euler studied Latin squares in the 1700s.
The four-colour theorem states that any map can be coloured using just four colours so that no two neighbouring regions share the same colour. It was proved in 1976 with the help of a computer.