LCM( 21, 45, 63, 81 ) = 2835
Step 1 : Place the numbers inside division bar:
21 | 45 | 63 | 81 |
Step 2 : Find a prime number which can divide at least two of your numbers.
In this example we can divide by 3. If any number is not divisible by 3 write it down unchanged.
3 | 21 | 45 | 63 | 81 |
7 | 15 | 21 | 27 |
Step 3 : Repeat Step 2 until you can no longer divide.
3 | 21 | 45 | 63 | 81 |
3 | 7 | 15 | 21 | 27 |
7 | 5 | 7 | 9 |
3 | 21 | 45 | 63 | 81 |
3 | 7 | 15 | 21 | 27 |
7 | 7 | 5 | 7 | 9 |
1 | 5 | 1 | 9 |
Since there are no primes that divides at least two of given numbers, we conclude that the LCM is a product of starting numbers.
LCM = 21 · 45 · 63 · 81 = 2835