LCM for 18 and 21
What's the Least Common Multiple (LCM) of 18 and 21?
(One hundred twenty-six)
Finding LCM for 18 and 21 using GCF's of these numbers
The first method to find LCM for numbers 18 and 21 is to find Greatest Common Factor (GCF) of these numbers. Here's the formula:
LCM = (Number1 × Number2) ÷ GCF
GCF of numbers 18 and 21 is 3, so
LCM = (18 × 21) ÷ 3
LCM = 378 ÷ 3
LCM = 126
Finding LCM for 18 and 21 by Listing Multiples
The second method to find LCM for numbers 18 and 21 is to list out the common multiples for both nubmers and pick the first which matching:
Multiples of 18: 18, 36, 54, 72, 90, 108, 126, 144, 162
Multiples of 21: 21, 42, 63, 84, 105, 126, 147, 168
So the LCM for 18 and 21 is 126
Finding LCM for 18 and 21 by Prime Factorization
Another method to find LCM for numbers 18 and 21 is to list all Prime Factors for both numbers and multiply the highest exponent prime factors:
All Prime Factors of 18: 2, 3, 3 (exponent form: 21, 32)
All Prime Factors of 21: 3, 7 (exponent form: 31, 71)
21 × 32 × 71 = 126
Related Calculations
See Also
- Greatest Common Factor - Find the Greatest Common Factor (GCF) of two numbers
<a href="https://calculat.io/en/number/least-common-multiple-lcm-of/18--21">What is the LCM of 18 and 21? - Calculatio</a>
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