The GCF of 8 and 16 is 8. The LCM of 8 and 16 is 16.
Factors of 8: 1, 2, 4, 8.
Factors of 16: 1, 2, 4, 8, 16.
Common factors: 1, 2, 4 and 8. The greatest of these is 8.
8 = 2 × 2 × 2
16 = 2 × 2 × 2 × 2
GCF: multiply the prime factors both numbers share: 2 × 2 × 2 = 8.
LCM: multiply every prime the maximum number of times it appears in either number: 2 × 2 × 2 × 2 = 16.
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 8, so GCF(8, 16) = 8.
Multiples of 8: 8, 16, 24, ...
Multiples of 16: 16, 32, ...
The first number in both lists is 16.
8 × 16 = 128 = 8 × 16. This always holds for two numbers, so you can find the LCM as (8 × 16) ÷ 8 = 16.
Divide the top and bottom by the GCF 8: 8/16 = 1/2.
| Numbers | GCF | LCM |
|---|---|---|
| 2 and 8 | 2 | 8 |
| 3 and 8 | 1 | 24 |
| 4 and 8 | 4 | 8 |
| 5 and 8 | 1 | 40 |
| 6 and 8 | 2 | 24 |
| 7 and 8 | 1 | 56 |
| 2 and 16 | 2 | 16 |
| 3 and 16 | 1 | 48 |
| 4 and 16 | 4 | 16 |
| 5 and 16 | 1 | 80 |
| 6 and 16 | 2 | 48 |
| 7 and 16 | 1 | 112 |
See also: factors of 8 · factors of 16 · 8/16 as a decimal.
Different numbers? Use the GCF and LCM calculator (any amount of numbers) or browse all GCF and LCM pairs.