LCM for 21 and 57
What's the Least Common Multiple (LCM) of 21 and 57?
(Three hundred ninety-nine)
Finding LCM for 21 and 57 using GCF's of these numbers
The first method to find LCM for numbers 21 and 57 is to find Greatest Common Factor (GCF) of these numbers. Here's the formula:
LCM = (Number1 × Number2) ÷ GCF
GCF of numbers 21 and 57 is 3, so
LCM = (21 × 57) ÷ 3
LCM = 1197 ÷ 3
LCM = 399
Finding LCM for 21 and 57 by Listing Multiples
The second method to find LCM for numbers 21 and 57 is to list out the common multiples for both nubmers and pick the first which matching:
Multiples of 21: 21, 42, 63, 84, 105, 126, 147, 168, 189, 210, 231, 252, 273, 294, 315, 336, 357, 378, 399, 420, 441
Multiples of 57: 57, 114, 171, 228, 285, 342, 399, 456, 513
So the LCM for 21 and 57 is 399
Finding LCM for 21 and 57 by Prime Factorization
Another method to find LCM for numbers 21 and 57 is to list all Prime Factors for both numbers and multiply the highest exponent prime factors:
All Prime Factors of 21: 3, 7 (exponent form: 31, 71)
All Prime Factors of 57: 3, 19 (exponent form: 31, 191)
31 × 71 × 191 = 399
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LCM Table
About "Least Common Multiple" Calculator
Least Common Multiple (LCM) also known as the Lowest Common Multiple or Smallest Common Multiple of 2 numbers - it is the smallest positive integer that is divisible by both numbers