The GCF of 15 and 60 is 15. The LCM of 15 and 60 is 60.
Factors of 15: 1, 3, 5, 15.
Factors of 60: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60.
Common factors: 1, 3, 5 and 15. The greatest of these is 15.
15 = 3 × 5
60 = 2 × 2 × 3 × 5
GCF: multiply the prime factors both numbers share: 3 × 5 = 15.
LCM: multiply every prime the maximum number of times it appears in either number: 2 × 2 × 3 × 5 = 60.
Divide the larger number by the smaller and repeat with the remainder until it is 0. The last non-zero remainder is the GCF.
The last non-zero remainder is 15, so GCF(15, 60) = 15.
Multiples of 15: 15, 30, 45, 60, 75, ...
Multiples of 60: 60, 120, ...
The first number in both lists is 60.
15 × 60 = 900 = 15 × 60. This always holds for two numbers, so you can find the LCM as (15 × 60) ÷ 15 = 60.
Divide the top and bottom by the GCF 15: 15/60 = 1/4.
| Numbers | GCF | LCM |
|---|---|---|
| 2 and 15 | 1 | 30 |
| 3 and 15 | 3 | 15 |
| 4 and 15 | 1 | 60 |
| 5 and 15 | 5 | 15 |
| 6 and 15 | 3 | 30 |
| 7 and 15 | 1 | 105 |
| 2 and 60 | 2 | 60 |
| 3 and 60 | 3 | 60 |
| 4 and 60 | 4 | 60 |
| 5 and 60 | 5 | 60 |
| 6 and 60 | 6 | 60 |
| 7 and 60 | 1 | 420 |
See also: factors of 15 · factors of 60.
Different numbers? Use the GCF and LCM calculator (any amount of numbers) or browse all GCF and LCM pairs.