Number reference
8 explained.
8: eight, composite, power of two; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- eight
- Classification
- composite
- Factors
- 1, 2, 4, 8
- Prime factorization
- 2 × 2 × 2
- Square root
- 2.828427
- Cube root
- 2
- Binary
- 1000
- Octal
- 10
- Hexadecimal
- 8
- Roman numeral
- VIII
- Digit sum
- 8
- Digital root
- 8
What makes 8 notable
- Power of two. 8 = 2^3, which is why it shows up in memory sizes, image dimensions, and anything that repeatedly halves or doubles.
- Perfect cube. 8 = 2³, so a cube of edge 2 has a volume of 8.
- Fibonacci number. 8 appears in the Fibonacci sequence, where each term is the sum of the two before it.
8 in everyday use
Eight bits make a byte, so 8 sits underneath every file size and memory figure in computing. It is the atomic number of oxygen and the number of legs on a spider or arms on an octopus. A musical octave spans eight notes of a scale, and the solar system has had eight planets since Pluto's reclassification in 2006. In Chinese the word for eight sounds like the word for prosperity, which is why the Beijing Olympics opened on 8 August 2008 at eight minutes past eight in the evening.
Eight is two cubed, the first cube after one, and the only positive cube that is also a Fibonacci number greater than one. In binary it is 1000, a single one followed by three zeros, which is why octal grouped bits in threes on early computers. It is the sixth Fibonacci number, the sum of 3 and 5. A number divides by 8 whenever its last three digits do, because 1000 is 8 × 125.
Nearby numbers
How to read this page
The factor list shows every way 8 splits into equal whole-number groups — 4 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 8 for contexts that do not use decimal.
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