100 101 → Ordinal 100th
(one hundredth) Roman numeral C | Cardinal one hundred Factorization 2× 5 | |

Divisors 1, 2, 4, 5, 10, 20, 25, 50, 100 |

**100** or **one hundred** (Roman numeral: **Ⅽ**) is the natural number following 99 and preceding 101.

## Contents

In medieval contexts, it may be described as the **short hundred** or five score in order to differentiate the English and Germanic use of "hundred" to describe the long hundred of six score or 120.

## In mathematics

100 is the square of 10 (in scientific notation it is written as 10^{2}). The standard SI prefix for a hundred is "hecto-".

100 is the basis of percentages (*per cent* meaning "per hundred" in Latin), with 100% being a full amount.

100 is the sum of the first nine prime numbers, as well as the sum of some pairs of prime numbers e.g., 3 + 97, 11 + 89, 17 + 83, 29 + 71, 41 + 59, and 47 + 53.

100 is the sum of the cubes of the first four integers (100 = 1^{3} + 2^{3} + 3^{3} + 4^{3}). This is related by Nicomachus's theorem to the fact that 100 also equals the square of the sum of the first four integers: 100 = 10^{2} = (1 + 2 + 3 + 4)^{2}.

2^{6} + 6^{2} = 100, thus 100 is a Leyland number.

100 is an 18-gonal number. It is divisible by the number of primes below it, 25 in this case. It can not be expressed as the difference between any integer and the total of coprimes below it, making it a noncototient. It can be expressed as a sum of some of its divisors, making it a semiperfect number.

100 is a Harshad number in base 10, and also in base 4, and in that base it is a self-descriptive number.

There are exactly 100 prime numbers whose digits are in strictly ascending order (e.g. 239, 2357 etc.).

100 is the smallest number whose common logarithm is a prime number (i.e. 10^{n} for which *n* is prime).

## In science

One hundred is the atomic number of fermium, an actinide.

On the Celsius scale, 100 degrees is the boiling temperature of pure water at sea level.

The Kármán line lies at an altitude of 100 kilometres above the Earth's sea level and is commonly used to define the boundary between Earth's atmosphere and outer space.

## In religion

## In politics

The United States Senate has 100 Senators.

## In money

Most of the world's currencies are divided into 100 subunits; for example, one euro is one hundred cents and one pound sterling is one hundred pence.

The 100 Euro banknotes feature a picture of a Rococo gateway on the obverse and a Baroque bridge on the reverse.

The U.S. hundred-dollar bill has Benjamin Franklin's portrait; the "Benjamin" is the largest U.S. bill in print. American savings bonds of $100 have Thomas Jefferson's portrait, while American $100 treasury bonds have Andrew Jackson's portrait.

## In other fields

**One hundred** is also: