Math & Numbers Facts for Kids
Mind-bending number facts
Take any four-digit number (with at least two different digits), arrange the digits in descending and ascending order, subtract the smaller from the larger, and repeat β you will always reach 6,174 within seven steps. This is called Kaprekar's constant.
Ancient Egyptians only used unit fractions, meaning fractions with 1 on top, such as Β½ or β . To write 2/3, they would write Β½ + β .
There are three different types of average: the mean (add all values and divide), the median (the middle value), and the mode (the most common value). They can give very different results from the same data set.
In Britain, a billion traditionally meant one million million (1,000,000,000,000), while in America it means one thousand million (1,000,000,000). Today, the American meaning is standard worldwide.
A tessellation is a pattern of shapes that tiles a flat surface with no gaps or overlaps. Triangles, squares, and hexagons are the only regular polygons that can tessellate on their own.
In a group of just 23 people, there is a greater than 50% chance that two of them share the same birthday. This surprising result is called the birthday paradox.
The circumference of any circle divided by its diameter always equals pi (Ο β 3.14159). This relationship holds for circles of every size, from a coin to a planet.
A MΓΆbius strip is a surface with only one side β if you draw a line along the middle without lifting your pen, you will return to your starting point having covered both sides. It is made by giving a strip of paper a half twist before joining the ends.
Any number multiplied by zero always equals zero. This rule, called the zero product property, holds true for every number in existence, including infinity in most mathematical contexts.
The word 'algebra' comes from the Arabic word 'al-jabr', which appeared in a 9th-century book by the mathematician Al-Khwarizmi. The word 'algorithm' also comes from his name.