LCM for 6 and 21

The first method to find LCM for numbers 6 and 21 is to find Greatest Common Factor (GCF) of these numbers. Here's the formula:

LCM = (Number1 × Number2) ÷ GCF

GCF of numbers 6 and 21 is 3, so

LCM = (6 × 21) ÷ 3

LCM = 126 ÷ 3

LCM = 42

The second method to find LCM for numbers 6 and 21 is to list out the common multiples for both nubmers and pick the first which matching:

Multiples of 6: 6, 12, 18, 24, 30, 36, 42, 48, 54

Multiples of 21: 21, 42, 63, 84

So the LCM for 6 and 21 is 42

Another method to find LCM for numbers 6 and 21 is to list all Prime Factors for both numbers and multiply the highest exponent prime factors: