GCF and LCM of 15
Every pair this site works through that contains 15. 25 of them share a factor with it; 10 share nothing, which is its own kind of answer.
Shares a factor with 15
Shares nothing with 15
What 15 is made of
Every common factor 15 can share with anything comes from this list, which is why the pairs below look the way they do. 15 = 3 × 5, and that factorisation is unique — the fundamental theorem of arithmetic guarantees no other set of primes multiplies to it.
- Divisors (4)
- 1, 3, 5, 15
- As factor pairs
- 1×15, 3×5
- Prime factorisation
- 3 × 5
- Divisors excluding itself add to
- 9 — deficient
Divisors come in pairs that multiply to 15, which is why there is an even number of them unless the number is a perfect square. The greatest common factor of 15 and any other number is the largest entry two lists like this one share.