GCF and LCM of 24 and 28

The GCF of 24 and 28 is 4. The LCM of 24 and 28 is 168.

Method 1: list the factors (GCF)

Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24.
Factors of 28: 1, 2, 4, 7, 14, 28.
Common factors: 1, 2 and 4. The greatest of these is 4.

Method 2: prime factorization

24 = 2 × 2 × 2 × 3
28 = 2 × 2 × 7

GCF: multiply the prime factors both numbers share: 2 × 2 = 4.

LCM: multiply every prime the maximum number of times it appears in either number: 2 × 2 × 2 × 3 × 7 = 168.

Method 3: Euclidean algorithm (GCF)

Divide the larger number by the smaller and repeat with the remainder until it is 0. The last non-zero remainder is the GCF.

  1. 28 = 1 × 24 + 4
  2. 24 = 6 × 4 + 0

The last non-zero remainder is 4, so GCF(24, 28) = 4.

LCM by listing multiples

Multiples of 24: 24, 48, 72, 96, 120, 144, 168, 192, ...
Multiples of 28: 28, 56, 84, 112, 140, 168, 196, ...
The first number in both lists is 168.

Check: GCF × LCM = product

4 × 168 = 672 = 24 × 28. This always holds for two numbers, so you can find the LCM as (24 × 28) ÷ 4 = 168.

Simplifying the fraction 24/28

Divide the top and bottom by the GCF 4: 24/28 = 6/7.

GCF and LCM of similar pairs

NumbersGCFLCM
2 and 24224
3 and 24324
4 and 24424
5 and 241120
6 and 24624
7 and 241168
2 and 28228
3 and 28184
4 and 28428
5 and 281140
6 and 28284
7 and 28728

See also: factors of 24 · factors of 28.

Different numbers? Use the GCF and LCM calculator (any amount of numbers) or browse all GCF and LCM pairs.