GCF and LCM of 7 and 24

The GCF of 7 and 24 is 1. The LCM of 7 and 24 is 168.

• GCF (greatest common factor, also called GCD or HCF) of 7 and 24 = 1
• LCM (least common multiple) of 7 and 24 = 168

7 and 24 share no common factor except 1, so they are coprime (relatively prime). When two numbers are coprime their LCM is simply their product: 7 × 24 = 168.

Method 1: list the factors (GCF)

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

Method 2: prime factorization

7 = 7 (prime)
24 = 2 × 2 × 2 × 3

GCF: multiply the prime factors both numbers share: there are none, so the GCF is 1.

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. 24 = 3 × 7 + 3
2. 7 = 2 × 3 + 1
3. 3 = 3 × 1 + 0

The last non-zero remainder is 1, so GCF(7, 24) = 1.

LCM by listing multiples

Multiples of 7: 7, 14, 21, 28, 35, 42, 49, 56, 63, ...
Multiples of 24: 24, 48, 72, 96, 120, 144, 168, 192, ...
The first number in both lists is 168.

Check: GCF × LCM = product

1 × 168 = 168 = 7 × 24. This always holds for two numbers, so you can find the LCM as (7 × 24) ÷ 1 = 168.

Simplifying the fraction 7/24

7/24 is already in lowest terms because the GCF of 7 and 24 is 1.

GCF and LCM of similar pairs

See also: factors of 7 · factors of 24 · 7/24 as a decimal.

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