Find Least Common Multiple of 12, 15 and 21 using ladder method..
Answer
LCM( 12, 15, 21 ) = 420
Explanation
Step 1 : Place the numbers inside division bar:
| 12 | 15 | 21 |
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 | 12 | 15 | 21 |
| 4 | 5 | 7 |
Step 4 : LCM is a product of numbers into L shape.
| 3 | 12 | 15 | 21 |
| 4 | 5 | 7 |
LCM = 3 · 4 · 5 · 7 = 420
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.
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