100 (number)

100 is a natural number that follows 99 and precedes 101. In the decimal system, it equals ten multiplied by ten, or 10². It is written as two zeros after a one.

Because it is a power of ten, 100 plays a major role in measurement, commerce, and proportion. The word 'percent' derives from the concept of dividing something into 100 equal parts.

Mathematical properties

100 is a perfect square, derived from 10, since 10 × 10 = 100. It is a composite number, meaning it has divisors other than 1 and itself. Its divisors are 1, 2, 4, 5, 10, 20, 25, 50, and 100. Its prime factorization is 2² × 5². In other base systems, 100 is written as 1100100 in binary and 64 in hexadecimal.

The sum of the first four natural numbers (1+2+3+4), when squared, equals 100. It is also equal to the sum of the first four cubes (1³+2³+3³+4³).

Use in measurement

The metric system consistently uses 100: one hundred centimeters equal one meter, and one hundred centigrams equal one gram. On the Celsius scale, the interval between the freezing and boiling points of water under standard conditions is divided into 100 degrees, which is why it is called 'centigrade.'

Cultural and administrative use

In many world currencies, the smallest unit equals one hundredth of the main unit: for example, one hundred cents make one dollar. Additionally, 100 years is called a century and is used to measure historical periods. Many parliaments and councils have around 100 members, though this figure is specific to each country.