80
LXXX
1010000
The number 80 — factors and divisors
Abundant
80 = 2⁴ × 5. It has 10 divisors, adding up to 186.
Its divisors, itself excluded, add up to more than the number.
Laid out as dots
It fits as 8 × 10. The more divisors, the closer to a square.
- Prime factors
- 2⁴ × 5
- Divisors
- 1, 2, 4, 5, 8, 10, 16, 20, 40, 80
- Sum of divisors
- 186
- Sum without itself
- 106
- Coprime below it
- 32
- Digit sum
- 8
- Digital root
- 8
- Roman numeral
- LXXX
- Binary
- 1010000
- Octal
- 120
- Hexadecimal
- 50
- Base 36
- 28
- Bits
- 7 bits
- Collatz steps
- 9 steps · peaks at 80
- Prime before
- 79
- Prime after
- 83
The grid
Ten per row, twenty rows. The filled cells are primes — you can see the multiples of 2 and 5 drop out in columns.
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Numbers either side
How to read this
- The prime factors are what the number is made of. The count and sum of divisors both follow from them.
- Add the divisors, take the number away, and you get perfect, abundant or deficient.
- The length of the binary form is the bit count. 255 taking eight digits is what a byte is.
- Collatz: halve it if even, triple it and add one if odd. The count is how many moves reach 1.
Frequently asked questions
Q. Is 80 a prime number?
No. It breaks down into 2⁴ × 5.
Q. What are the divisors of 80?
1, 2, 4, 5, 8, 10, 16, 20, 40, 80 — 10 divisors in all, adding up to 186.
Q. How is 80 written in binary?
1010000, which is 7 bits. In hexadecimal it is 50.
Q. How many Collatz steps does 80 take?
It reaches 1 in 9, peaking at 80 on the way.