100
C
1100100
The number 100 — factors and divisors
Abundant
100 = 2² × 5². It has 9 divisors, adding up to 217.
Its divisors, itself excluded, add up to more than the number.
Families it belongs to
Square
A number times itself — the dots lay out as a square.
Laid out as dots
It fits as 10 × 10. The more divisors, the closer to a square.
- Prime factors
- 2² × 5²
- Divisors
- 1, 2, 4, 5, 10, 20, 25, 50, 100
- Sum of divisors
- 217
- Sum without itself
- 117
- Coprime below it
- 40
- Digit sum
- 1
- Digital root
- 1
- Roman numeral
- C
- Binary
- 1100100
- Octal
- 144
- Hexadecimal
- 64
- Base 36
- 2S
- Bits
- 7 bits
- Collatz steps
- 25 steps · peaks at 100
- Prime before
- 97
- Prime after
- 101
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 100 a prime number?
No. It breaks down into 2² × 5².
Q. What are the divisors of 100?
1, 2, 4, 5, 10, 20, 25, 50, 100 — 9 divisors in all, adding up to 217.
Q. How is 100 written in binary?
1100100, which is 7 bits. In hexadecimal it is 64.
Q. How many Collatz steps does 100 take?
It reaches 1 in 25, peaking at 100 on the way.