How do I find LCM and HCF of 12, 18, and 24 using prime factorisation?
I know how to do HCF and LCM of two numbers but I get confused with three numbers. Is the method the same? Also, can I verify my answer using the formula HCF*LCM = product of numbers?
1 Answer
PIPooja Iyer
✓ Accepted
· 15d ago
▲ 7
Prime factorisation: 12 = 2^2 * 3. 18 = 2 * 3^2. 24 = 2^3 * 3. HCF = product of LOWEST powers of common factors = 2^1 * 3^1 = 6. LCM = product of HIGHEST powers of all factors = 2^3 * 3^2 = 8 * 9 = 72. Verification warning: The formula HCF * LCM = product of numbers works ONLY for TWO numbers. For three numbers: HCF(12,18,24) * LCM(12,18,24) = 6 * 72 = 432, but 121824 = 5184. They are NOT equal! Do not use that formula for three numbers. For three numbers, just directly use prime factorisation to find HCF (lowest powers) and LCM (highest powers).
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