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GCF & LCM Calculator

Find the Greatest Common Factor (GCF) and Least Common Multiple (LCM) of two or more numbers. Works with any number of integers.

FREE MULTI-NUMBER
GCF (Greatest Common Factor)
LCM (Least Common Multiple)
Numbers:

📐 Formulas

GCF using Euclidean Algorithm
GCF(a, b) = GCF(b, a mod b) until b = 0
LCM from GCF
LCM(a, b) = |a × b| / GCF(a, b)

💡 Examples

Numbers: 12, 18

GCF = 6 | LCM = 36

12 = 2×2×3, 18 = 2×3×3 → shared: 2×3 = 6

Numbers: 8, 12, 20

GCF = 4 | LCM = 120

❓ FAQ

Use GCF when simplifying fractions (divide numerator and denominator by the GCF). Use LCM when finding a common denominator to add or subtract fractions, or when finding when two periodic events will coincide.

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💡 Quick Tip

To simplify a fraction like 18/24, divide both by GCF(18, 24) = 6, giving you 3/4.