Find Least Common Multiple of 21, 28, 36 and 45 using division method..
Answer
LCM( 21, 28, 36, 45 ) = 1260
Explanation
Step 1 : Write the given numbers in a horizontal line.
| 21 | 28 | 36 | 45 |
Step 2 : Divide the given numbers by smallest prime number. In this example we can divide by 2.
(if any number is not divisible by 2, write it down unchanged)
| 2 | 21 | 28 | 36 | 45 |
| 21 | 14 | 18 | 45 |
Step 3 : Continue dividing by prime numbers till we get 1 in all columns.
| 2 | 21 | 28 | 36 | 45 |
| 2 | 21 | 14 | 18 | 45 |
| 3 | 21 | 7 | 9 | 45 |
| 3 | 7 | 7 | 3 | 15 |
| 5 | 7 | 7 | 1 | 5 |
| 7 | 7 | 7 | 1 | 1 |
| 1 | 1 | 1 | 1 |
Step 4 : Multiply numbers in first column to get LCM.
LCM( 21, 28, 36, 45 ) = 2 · 2 · 3 · 3 · 5 · 7 = 1260 .
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