LCM for 5 and 21
What's the Least Common Multiple (LCM) of 5 and 21?
(One hundred five)
Finding LCM for 5 and 21 using GCF's of these numbers
The first method to find LCM for numbers 5 and 21 is to find Greatest Common Factor (GCF) of these numbers. Here's the formula:
LCM = (Number1 × Number2) ÷ GCF
GCF of numbers 5 and 21 is 1, so
LCM = (5 × 21) ÷ 1
LCM = 105 ÷ 1
LCM = 105
Finding LCM for 5 and 21 by Listing Multiples
The second method to find LCM for numbers 5 and 21 is to list out the common multiples for both nubmers and pick the first which matching:
Multiples of 5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115
Multiples of 21: 21, 42, 63, 84, 105, 126, 147
So the LCM for 5 and 21 is 105
Finding LCM for 5 and 21 by Prime Factorization
Another method to find LCM for numbers 5 and 21 is to list all Prime Factors for both numbers and multiply the highest exponent prime factors:
All Prime Factors of 5: 5 (exponent form: 51)
All Prime Factors of 21: 3, 7 (exponent form: 31, 71)
51 × 31 × 71 = 105
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/5--21">What is the LCM of 5 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