Find Least Common Multiple of 2, 5 and 7 using prime factorisation method.
Answer
LCM( 2, 5, 7 ) = 70
Explanation
Step 1: Write down factorisation of each number:
2 = 2
5 = 5
7 = 7
Step 2 : Match primes vertically:
| 2 | = | 2 | ||||
| 5 | = | 5 | ||||
| 7 | = | 7 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
| 2 | = | 2 | ||||||
| 5 | = | 5 | ||||||
| 7 | = | 7 | ||||||
| LCM | = | 2 | · | 5 | · | 7 | = | 70 |
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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