Least Common Multiple (LCM) of 21 and 28
The least common multiple (LCM) of 21 and 28 is 84.
What is the Least Common Multiple (LCM)?
The LCM of two integers is the smallest positive integer that is divisible by both numbers. It is often used to find common denominators and solve problems involving periodic events.
Formula for LCM
The LCM of two numbers can be calculated using their GCD:
LCM(a, b) = |a × b| ÷ GCD(a, b)
How to Calculate the LCM of 21 and 28?
First, calculate the GCD of 21 and 28 using the Euclidean algorithm. Then use the formula above to find the LCM.
Step-by-Step GCD Calculation
| Step | Calculation |
|---|---|
| 1 | 21 ÷ 28 = 0 remainder 21 |
| 2 | 28 ÷ 21 = 1 remainder 7 |
| 3 | 21 ÷ 7 = 3 remainder 0 |
Examples of LCM Calculations
| Numbers | LCM |
|---|---|
| 188 and 49 | 9212 |
| 54 and 102 | 918 |
| 108 and 63 | 756 |
| 42 and 132 | 924 |
| 52 and 155 | 8060 |