LCM for 21 and 72
What's the Least Common Multiple (LCM) of 21 and 72?
(Five hundred four)
Finding LCM for 21 and 72 using GCF's of these numbers
The first method to find LCM for numbers 21 and 72 is to find Greatest Common Factor (GCF) of these numbers. Here's the formula:
LCM = (Number1 × Number2) ÷ GCF
GCF of numbers 21 and 72 is 3, so
LCM = (21 × 72) ÷ 3
LCM = 1512 ÷ 3
LCM = 504
Finding LCM for 21 and 72 by Listing Multiples
The second method to find LCM for numbers 21 and 72 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, 462, 483, 504, 525, 546
Multiples of 72: 72, 144, 216, 288, 360, 432, 504, 576, 648
So the LCM for 21 and 72 is 504
Finding LCM for 21 and 72 by Prime Factorization
Another method to find LCM for numbers 21 and 72 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 72: 2, 2, 2, 3, 3 (exponent form: 23, 32)
32 × 71 × 23 = 504
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/21--72">What is the LCM of 21 and 72? - 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