Math & Numbers Facts for Kids
Mind-bending number facts
The Moon's gravity is about one sixth of Earth's, so you would weigh six times less on the Moon. A child weighing 30 kg on Earth would weigh only 5 kg on the Moon.
In a decimal number, the first digit after the decimal point represents tenths, the second represents hundredths, and the third represents thousandths. So 0.375 means 3 tenths + 7 hundredths + 5 thousandths.
Factors are numbers that divide evenly into a given number (factors of 12: 1, 2, 3, 4, 6, 12), while multiples are numbers in a given number's times table (multiples of 12: 12, 24, 36β¦). The two concepts are opposite directions of the same relationship.
Ancient Chinese mathematicians used red rods for positive numbers and black rods for negative numbers on counting boards around 200 BC β the opposite of how modern banks display negative balances.
Our everyday number system uses base 10 (ten digits: 0β9), but computers use base 2 (binary), base 8 (octal), and base 16 (hexadecimal). Programmers use these different bases when writing software.
The sum of interior angles in any polygon can be found using the formula (n β 2) Γ 180Β°, where n is the number of sides. A pentagon has (5 β 2) Γ 180Β° = 540Β°.
A trillion is 1,000,000,000,000, or 10ΒΉΒ². Scientists often use scientific notation to write very large or very small numbers neatly, such as 6.67 Γ 10β»ΒΉΒΉ for the gravitational constant.
Division by zero is undefined in mathematics β there is no meaningful answer to 5 Γ· 0. If you type it into a calculator, it will display an error, because the operation breaks the rules of arithmetic.
In an arithmetic sequence, the difference between consecutive terms is always the same. The sequence 3, 7, 11, 15, 19 has a common difference of 4.
In a geometric sequence, each term is multiplied by the same number to get the next one. The sequence 2, 6, 18, 54, 162 has a common ratio of 3.