30
XXX
11110
The number 30 — factors and divisors
Abundant
30 = 2 × 3 × 5. It has 8 divisors, adding up to 72.
Its divisors, itself excluded, add up to more than the number.
Laid out as dots
It fits as 5 × 6. The more divisors, the closer to a square.
- Prime factors
- 2 × 3 × 5
- Divisors
- 1, 2, 3, 5, 6, 10, 15, 30
- Sum of divisors
- 72
- Sum without itself
- 42
- Coprime below it
- 8
- Digit sum
- 3
- Digital root
- 3
- Roman numeral
- XXX
- Binary
- 11110
- Octal
- 36
- Hexadecimal
- 1E
- Base 36
- U
- Bits
- 5 bits
- Collatz steps
- 18 steps · peaks at 160
- Prime before
- 29
- Prime after
- 31
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 30 a prime number?
No. It breaks down into 2 × 3 × 5.
Q. What are the divisors of 30?
1, 2, 3, 5, 6, 10, 15, 30 — 8 divisors in all, adding up to 72.
Q. How is 30 written in binary?
11110, which is 5 bits. In hexadecimal it is 1E.
Q. How many Collatz steps does 30 take?
It reaches 1 in 18, peaking at 160 on the way.