# 100 (number)

100 (the Roman numeral is C for centum) is the natural number following 99 and preceding 101.

 List of numbers — Integers << 100 101 102 103 104 105 106 107 108 109 >>
Cardinal one hundred
Ordinal 100th (one hundredth)
Factorization [itex]2^2 \cdot 5^2[itex]
Divisors 2, 4, 5, 10,
20, 25, 50
Roman numeral C
Unicode representation of Roman numeral Ⅽ, ⅽ
prefixes hecto-/hect- (from Greek)

centi- (from Latin)

Binary 1100100
Hebrew ק (Qof)
 Contents

## In mathematics

One hundred is the square of 10 (in scientific notation it is written as [itex]10^2[itex]). The standard SI prefix for a hundred is "hecto-".

It is the sum of the first nine prime numbers, as well as the sum of two prime numbers (47 + 53), and the sum of the cubes of the first four integers.

But perhaps this number is most important as the basis of percentages (literally "per hundred"), with 100% being a full amount.

One hundred is also an 18-gonal number. It is divisible by the number of primes below it, 25 in this case. But it can not be expressed as the difference between any integer and the total of coprimes below it, making it a noncototient.

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

## In science

In astronomy,

Messier object M100, a magnitude 10.5 spiral galaxy in the constellation Coma Berenices
The New General Catalogue object (http://www.ngcic.org/) NGC 100, a magnitude 13.3 spiral galaxy in the constellation Pisces
The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/SEsaros/SEsaros1-175.html) of the solar eclipse series which began on 264 May 13 and ended on 1526 June 10. The duration of Saros series 100 was 1262.1 years, and it contained 71 solar eclipses.
The Saros number (http://sunearth.gsfc.nasa.gov/eclipse/LEsaros/LEsaros1-175.html) of the lunar eclipse series which began on 403 November 15 and ended on 1864 April 22. The duration of Saros series 100 was 1460.4 years, and it contained 82 lunar eclipses.

## In other fields

Missing image
Sxc_100.jpg
The Number 100

One hundred is also:

## Other numbers in the 100s

• Art and Cultures
• Countries of the World (http://www.academickids.com/encyclopedia/index.php/Countries)
• Space and Astronomy