Number reference
900 explained.
900: nine hundred, composite, perfect square; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- nine hundred
- Classification
- composite
- Factors
- 1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 25, 30, 36, 45, 50, 60, 75, 90, 100, 150, 180, 225, 300, 450, 900
- Prime factorization
- 2 × 2 × 3 × 3 × 5 × 5
- Square root
- 30
- Cube root
- 9.654894
- Binary
- 1110000100
- Octal
- 1604
- Hexadecimal
- 384
- Roman numeral
- CM
- Digit sum
- 9
- Digital root
- 9
What makes 900 notable
- Perfect square. 900 = 30², so a square of side 30 has an area of 900.
900 in everyday use
Nine hundred is thirty squared, CM in Roman numerals, and the number of seconds in a quarter of an hour. In the United States the 900 prefix marked premium-rate telephone lines from the 1980s, charged by the minute for horoscopes, chat, and contests, until abuse and regulation drove them out of use. The 900 MHz band carries cordless phones and many industrial radios, and a "900" is a two-and-a-half-turn trick in skateboarding, first landed in competition by Tony Hawk in 1999.
That trick name follows from geometry: 900 degrees is two and a half full turns, and it is also the sum of the interior angles of a heptagon, since (7 − 2) × 180 = 900. The number factors as 2² × 3² × 5², a square of 30, and has 27 divisors. It is 1110000100 in binary and 384 in hexadecimal. Its digit sum is 9, which divides it, so it is a Harshad number.
Nearby numbers
How to read this page
The factor list shows every way 900 splits into equal whole-number groups — 27 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 900 for contexts that do not use decimal.
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