Math & Numbers Facts for Kids
Mind-bending number facts
A circle encloses the most area for a given perimeter of any shape. That is why bubbles are round β nature automatically finds the most efficient shape when surface tension pulls a bubble tight.
The four color theorem states that any map can be colored using only four colors so that no two neighboring regions share the same color. It was famously the first major theorem proven with the help of a computer, in 1976.
When you multiply two numbers, the order doesn't matter β 4 Γ 7 gives the same answer as 7 Γ 4. Mathematicians call this the commutative property, and it works for addition too, but not for subtraction or division.
Pascal's Triangle is a triangle of numbers where each number is the sum of the two above it. Hidden inside it are the Fibonacci sequence, powers of 2, and dozens of other mathematical patterns.
Roman numerals struggled to represent fractions easily, so Romans used a separate system based on twelfths for everyday measurements. The word 'ounce' and 'inch' both come from the Latin word for one-twelfth.
Any number ending in 5, when squared, always ends in 25. For example, 15Β² = 225 and 85Β² = 7225. You can quickly calculate 65Β² by multiplying 6 Γ 7 = 42, then appending 25 to get 4225.
A sphere holds the greatest volume for any given surface area. This is why planets and stars are spherical β gravity pulls matter into the shape that uses the least energy, which is a sphere.
The Indian mathematician Brahmagupta, born in 598 CE, was one of the first to establish rules for arithmetic with zero and negative numbers. He described how multiplying two negative numbers gives a positive result.
The tangram is a Chinese puzzle made of seven flat pieces that fit together to form a square. By rearranging the pieces, you can create over 6,500 different shapes, exploring geometry through play.
100 is 10 squared, 1,000 is 10 cubed, and so on. Our entire decimal number system is built around powers of 10 β almost certainly because humans have 10 fingers.