Number reference
80 explained.
80: eighty, composite; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- eighty
- Classification
- composite
- Factors
- 1, 2, 4, 5, 8, 10, 16, 20, 40, 80
- Prime factorization
- 2 × 2 × 2 × 2 × 5
- Square root
- 8.944272
- Cube root
- 4.308869
- Binary
- 1010000
- Octal
- 120
- Hexadecimal
- 50
- Roman numeral
- LXXX
- Digit sum
- 8
- Digital root
- 8
What makes 80 notable
- Factor structure. 80 breaks down into 2 distinct primes (2, 5) and has 10 divisors in total, so it can be split into equal whole-number groups 8 ways beyond 1 and itself.
80 in everyday use
Port 80 is where web servers listen for unencrypted HTTP traffic, so nearly every web address before the rise of HTTPS was quietly talking to port 80. Eighty is the atomic number of mercury, the only metal liquid at room temperature. Jules Verne's Phileas Fogg went around the world in eighty days, French counts 80 as quatre-vingts, "four twenties", and the Pareto principle holds that roughly 80 percent of effects come from 20 percent of causes. Punch cards held 80 columns.
Eighty is 2⁴ × 5 and has ten divisors. It is the sum of a cube and a square, 64 + 16, which happens to be 4² + 8² as well, so it is a sum of two squares too. It is a semiperfect number, since 40 + 20 + 16 + 4 = 80. In binary it is 1010000.
Nearby numbers
How to read this page
The factor list shows every way 80 splits into equal whole-number groups — 10 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 80 for contexts that do not use decimal.
Percentage calculator · Fraction calculator · Browse Number Explorer