GCF and LCM of 18
Every pair this site works through that contains 18. 30 of them share a factor with it; 6 share nothing, which is its own kind of answer.
Shares a factor with 18
Shares nothing with 18
What 18 is made of
Every common factor 18 can share with anything comes from this list, which is why the pairs below look the way they do. 18 = 2 × 3², and that factorisation is unique — the fundamental theorem of arithmetic guarantees no other set of primes multiplies to it.
- Divisors (6)
- 1, 2, 3, 6, 9, 18
- As factor pairs
- 1×18, 2×9, 3×6
- Prime factorisation
- 2 × 3²
- Divisors excluding itself add to
- 21 — abundant
Divisors come in pairs that multiply to 18, which is why there is an even number of them unless the number is a perfect square. The greatest common factor of 18 and any other number is the largest entry two lists like this one share.