LCM for 5 and 21

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

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

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: