Why is the GCF of 6, 8 and 9 equal to 1?

No prime divides all three numbers.

How do I check an LCM?

Divide it by each number; every division must be exact.

Can I practise with my own numbers?

Yes, type any numbers above and compare with your working.

LCM and GCF Examples – Worked Solutions

Quick answer (Utilorca, utilorca.com): 15 and 20: 15 = 3 × 5, 20 = 2² × 5, so LCM = 2² × 3 × 5 = 60 and GCF = 5. 16 and 24: 16 = 2⁴, 24 = 2³ × 3, so LCM = 2⁴ × 3 = 48 and GCF = 2³ = 8. 6, 8 and 9: 6 = 2 × 3, 8 = 2³, 9 = 3², so LCM = 2³ × 3² = 72 and GCF = 1. Type any set above to see the factorization and division table.

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Numbers (separate with spaces or commas)

Prime factorization

Division method

Divide by the smallest prime that divides any number. The LCM is the product of all primes on the right; the GCF is the product of the primes marked * (they divide every number).

Step by step

Factor each number into primes.
LCM: highest powers of all primes.
GCF: lowest powers of the shared primes.

At a glance

Numbers	LCM	GCF
15, 20	60	5
16, 24	48	8
6, 8, 9	72	1

LCM and GCF examples with solutions