The GCF of 18 and 36 is 18. The LCM of 18 and 36 is 36.
Factors of 18: 1, 2, 3, 6, 9, 18.
Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36.
Common factors: 1, 2, 3, 6, 9 and 18. The greatest of these is 18.
18 = 2 × 3 × 3
36 = 2 × 2 × 3 × 3
GCF: multiply the prime factors both numbers share: 2 × 3 × 3 = 18.
LCM: multiply every prime the maximum number of times it appears in either number: 2 × 2 × 3 × 3 = 36.
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 18, so GCF(18, 36) = 18.
Multiples of 18: 18, 36, 54, ...
Multiples of 36: 36, 72, ...
The first number in both lists is 36.
18 × 36 = 648 = 18 × 36. This always holds for two numbers, so you can find the LCM as (18 × 36) ÷ 18 = 36.
Divide the top and bottom by the GCF 18: 18/36 = 1/2.
| Numbers | GCF | LCM |
|---|---|---|
| 2 and 18 | 2 | 18 |
| 3 and 18 | 3 | 18 |
| 4 and 18 | 2 | 36 |
| 5 and 18 | 1 | 90 |
| 6 and 18 | 6 | 18 |
| 7 and 18 | 1 | 126 |
| 2 and 36 | 2 | 36 |
| 3 and 36 | 3 | 36 |
| 4 and 36 | 4 | 36 |
| 5 and 36 | 1 | 180 |
| 6 and 36 | 6 | 36 |
| 7 and 36 | 1 | 252 |
See also: factors of 18 · factors of 36.
Different numbers? Use the GCF and LCM calculator (any amount of numbers) or browse all GCF and LCM pairs.