LCM for 5 and 21

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What's the Least Common Multiple (LCM) of 5 and 21?

Answer

LCM of 5 and 21 is
105

First common multiples: 105, 210, 315, …

105 is divisible by both: 105 ÷ 5 = 21, 105 ÷ 21 = 5 — and 21 and 5 share no factor but 1, so no smaller number is. As a common denominator: multiply the top and bottom of x/5 by 21 and of y/21 by 5.

5 and 21 are coprime (GCF = 1), so their LCM is simply the product: 5 × 21 = 105.

5 — prime

21 = 3 × 7

Prime521Highest power
3—33
55—5
7—77

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

LCM = 3 × 5 × 7 = 105

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LCM Table

Number 1Number 2LCM
5630
5735
5840
5945
51010
51155
51260
51365
51470
51515
51680
51785
51890
51995
52020
521105
522110
524120
52525
526130
527135
53030
531155
532160
53535
539195
54040
543215
544220
54545

FAQ

What's the Least Common Multiple (LCM) of 5 and 21?

LCM of 5 and 21 is 105

How to find the LCM of 5 and 21 using prime factorization?

To find the LCM of 5 and 21, find all prime factors of both numbers, then multiply the highest power of each prime factor. The result is 105.

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 5 and 21: LCM = 105, GCF = 1.

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