Least Common Multiple (LCM) of 15 and 21
The least common multiple (LCM) of 15 and 21 is 105.
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 15 and 21?
First, calculate the GCD of 15 and 21 using the Euclidean algorithm. Then use the formula above to find the LCM.
Step-by-Step GCD Calculation
| Step | Calculation |
|---|---|
| 1 | 15 ÷ 21 = 0 remainder 15 |
| 2 | 21 ÷ 15 = 1 remainder 6 |
| 3 | 15 ÷ 6 = 2 remainder 3 |
| 4 | 6 ÷ 3 = 2 remainder 0 |
Examples of LCM Calculations
| Numbers | LCM |
|---|---|
| 178 and 61 | 10858 |
| 19 and 157 | 2983 |
| 29 and 170 | 4930 |
| 148 and 46 | 3404 |
| 152 and 115 | 17480 |