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LCM of 6 and 9

The least common multiple (LCM) of 6 and 9 is 18. Their greatest common factor (GCF) is 3.

LCM18
GCF3
Prime factors of 62 × 3
Prime factors of 93^2

Prime factorization method

Write each number as a product of primes: 6 = 2 × 3 and 9 = 3^2. The LCM takes every prime with its highest power, which gives 18. The GCF takes only the shared primes with their lowest power, which gives 3.

Check with the formula

For two numbers, LCM × GCF = a × b. Here 18 × 3 = 54, and 6 × 9 = 54, so the answer is correct.

Multiples of 6 and 9

Multiples of 6: 6, 12, 18, 24, 30, 36, 42, 48 … Multiples of 9: 9, 18, 27, 36, 45, 54, 63, 72 … The first number that appears in both lists is 18.

Open the LCM & GCF Calculator

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Frequently asked questions

What is the LCM of 6 and 9?

The LCM of 6 and 9 is 18. It is the smallest positive number that both 6 and 9 divide into exactly.

What is the GCF of 6 and 9?

The greatest common factor of 6 and 9 is 3. It is the largest number that divides both without a remainder.

How do I find the LCM of 6 and 9 quickly?

Divide the product by the GCF: 6 × 9 = 54, and 54 ÷ 3 = 18.