LCM for 21 and 47

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What's the Least Common Multiple (LCM) of 21 and 47?

Answer

LCM of 21 and 47 is
987

First common multiples: 987; 1,974; 2,961; …

987 is divisible by both: 987 ÷ 21 = 47, 987 ÷ 47 = 21 — and 47 and 21 share no factor but 1, so no smaller number is. As a common denominator: multiply the top and bottom of x/21 by 47 and of y/47 by 21.

21 and 47 are coprime (GCF = 1), so their LCM is simply the product: 21 × 47 = 987.

21 = 3 × 7

47 — prime

Prime2147Highest power
33—3
77—7
47—4747

— = power 0: the prime is not a factor of this number; the LCM takes it from the number that has it.

LCM = 3 × 7 × 47 = 987

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FAQ

What's the Least Common Multiple (LCM) of 21 and 47?

LCM of 21 and 47 is 987

How to find the LCM of 21 and 47 using prime factorization?

To find the LCM of 21 and 47, find all prime factors of both numbers, then multiply the highest power of each prime factor. The result is 987.

What is the difference between LCM and GCF?

LCM (Least Common Multiple) is the smallest number divisible by both numbers, while GCF (Greatest Common Factor) is the largest number that divides both. For 21 and 47: LCM = 987, GCF = 1.