Least Common Multiple (LCM) of 21 and 42
The least common multiple (LCM) of 21 and 42 is 42.
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 42?
First, calculate the GCD of 21 and 42 using the Euclidean algorithm. Then use the formula above to find the LCM.
Step-by-Step GCD Calculation
| Step | Calculation |
|---|---|
| 1 | 21 ÷ 42 = 0 remainder 21 |
| 2 | 42 ÷ 21 = 2 remainder 0 |
Examples of LCM Calculations
| Numbers | LCM |
|---|---|
| 14 and 128 | 896 |
| 21 and 11 | 231 |
| 64 and 122 | 3904 |
| 72 and 130 | 4680 |
| 44 and 39 | 1716 |