Find Least Common Multiple of 6, 12, 30 and 40 using ladder method..
Answer
LCM( 6, 12, 30, 40 ) = 120
Explanation
Step 1 : Place the numbers inside division bar:
| 6 | 12 | 30 | 40 |
Step 2 : Find a prime number which can divide at least two of your numbers.
In this example we can divide by 2. If any number is not divisible by 2 write it down unchanged.
| 2 | 6 | 12 | 30 | 40 |
| 3 | 6 | 15 | 20 |
Step 3 : Repeat Step 2 until you can no longer divide.
| 2 | 6 | 12 | 30 | 40 |
| 2 | 3 | 6 | 15 | 20 |
| 3 | 3 | 15 | 10 |
| 2 | 6 | 12 | 30 | 40 |
| 2 | 3 | 6 | 15 | 20 |
| 3 | 3 | 3 | 15 | 10 |
| 1 | 1 | 5 | 10 |
| 2 | 6 | 12 | 30 | 40 |
| 2 | 3 | 6 | 15 | 20 |
| 3 | 3 | 3 | 15 | 10 |
| 5 | 1 | 1 | 5 | 10 |
| 1 | 1 | 1 | 2 |
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 = 6 · 12 · 30 · 40 = 120
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