100

In mathematics

100 is the square of 10 (in scientific notation it is written as 102). The standard SI prefix for a hundred is "hecto-".

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

100 is a Harshad number in decimal, and also in base-four, a base in-which it is also a self-descriptive number.

100 is the sum of the first nine prime numbers, from 2 through 23. It is also divisible by the number of primes below it, 25.

100 cannot be expressed as the difference between any integer and the total of coprimes below it, making it a noncototient.

100 has a reduced totient of 20, and an Euler totient of 40. A totient value of 100 is obtained from four numbers: 101, 125, 202, and 250.

100 can be expressed as a sum of some of its divisors, making it a semiperfect number. The geometric mean of its nine divisors is 10.

100 is the sum of the cubes of the first four positive integers (100 = 13 + 23 + 33 + 43). This is related by Nicomachus's theorem to the fact that 100 also equals the square of the sum of the first four positive integers: .

100 = 26 + 62, thus 100 is the seventh Leyland number. 100 is also the seventeenth Erdős–Woods number, and the fourth 18-gonal number.

It is the 10th star number (whose digit sum also adds to 10 in decimal).

In history

• 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 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.

By specification, 100 euro notes feature a picture of a Rococo gateway on the obverse and a Baroque bridge on the reverse.

The United States one-hundred-dollar bill has Benjamin Franklin's portrait; this "Benjamin" is the largest American banknote in circulation.

In other fields

Computers and software

• The HTTP status code indicating that the client should continue with its request.
• 100 Mbps Ethernet: Fast Ethernet standard.

Science and measurement

In zoology, the group of centipedes (Chilopoda) is classified as a subclass of millipedes. Centipedes are characterised by having between 15 and 191 pairs of legs. Although the name refers to "hundred", the actual number varies gradually.

With regard to the biological value of proteins, the number 100 is used as a reference value: the biological value of a protein is measured by how well the dietary protein can be converted into the body's own protein. The chicken egg was arbitrarily set at a value of 100, and other proteins are evaluated relative to this.

Anders Celsius defined 100° as the boiling point and 0° as the melting point of water for his temperature scale. In 1744, shortly after Celsius' death, the modern Celsius scale was introduced by Carl von Linné, in which the boiling point of water is assigned the value 100°C and the freezing point the value 0°C.

• 100 centimetres = 1 meter: Used in metric measurements.
• 100 is the atomic number of Fermium (Fm): A synthetic chemical element in the periodic table.

Sports

• 100-meter sprint: One of the most prestigious Olympic events.

Culture

• 100 emoji 💯: Commonly used to represent something excellent or perfect.

References

• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 133

References

1. "Sloane's A005349 : Niven (or Harshad) numbers". OEIS Foundation.
2. {{Cite OEIS. A108551. Self-descriptive numbers in various bases represented in base 10
3. {{cite OEIS. A007504. Sum of the first n primes.
4. {{cite OEIS. A057809. Numbers n such that pi(n) divides n.
5. {{Cite OEIS. A005278. Noncototients
6. {{Cite OEIS. A002322. Reduced totient function
7. {{Cite OEIS. A000010. Euler totient function
8. {{Cite OEIS. A005835. Pseudoperfect (or semiperfect) numbers n
9. {{Cite OEIS. A025403. Numbers that are the sum of 4 positive cubes in exactly 1 way.
10. {{Cite OEIS. A000537
11. "Sloane's A076980 : Leyland numbers". OEIS Foundation.
12. {{Cite OEIS. A059756. Erdős-Woods numbers: the length of an interval of consecutive integers with property that every element has a factor in common with one of the endpoints
13. "Sloane's A051870 : 18-gonal numbers". OEIS Foundation.
14. {{Cite OEIS. A003154