LCM for 21 and 14
What's the Least Common Multiple (LCM) of 21 and 14?
Answer
(Forty-two)
Finding LCM for 21 and 14 using GCF of these numbers
The first method to find LCM for numbers 21 and 14 is to find Greatest Common Factor (GCF) of these numbers. Here's the formula:
LCM = (Number1 × Number2) ÷ GCF
GCF of numbers 21 and 14 is 7, so
LCM = (21 × 14) ÷ 7
LCM = 294 ÷ 7
LCM = 42
Finding LCM for 21 and 14 by Listing Multiples
The second method to find LCM for numbers 21 and 14 is to list out the common multiples for both numbers and pick the first one that matches:
Multiples of 21: 21, 42, 63, 84
Multiples of 14: 14, 28, 42, 56, 70
So the LCM for 21 and 14 is 42
Finding LCM for 21 and 14 by Prime Factorization
Another method to find LCM for numbers 21 and 14 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 14: 2, 7 (exponent form: 21, 71)
31 × 71 × 21 = 42
See Also
- Greatest Common Factor - Find the Greatest Common Factor (GCF) of two numbers

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