Least Common Multiple (LCM) of 21 and 81
The least common multiple (LCM) of 21 and 81 is 567.
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 81?
First, calculate the GCD of 21 and 81 using the Euclidean algorithm. Then use the formula above to find the LCM.
Step-by-Step GCD Calculation
| Step | Calculation |
|---|---|
| 1 | 21 ÷ 81 = 0 remainder 21 |
| 2 | 81 ÷ 21 = 3 remainder 18 |
| 3 | 21 ÷ 18 = 1 remainder 3 |
| 4 | 18 ÷ 3 = 6 remainder 0 |
Examples of LCM Calculations
| Numbers | LCM |
|---|---|
| 99 and 101 | 9999 |
| 101 and 39 | 3939 |
| 156 and 78 | 156 |
| 84 and 181 | 15204 |
| 160 and 45 | 1440 |