Find Least Common Multiple of 1, 4 and 5 using prime factorisation method.
Answer
LCM( 1, 4, 5 ) = 20
Explanation
Step 1: Write down factorisation of each number:
1 = 1
4 = 2 · 2
5 = 5
Step 2 : Match primes vertically:
| 1 | = | 1 | ||||||
| 4 | = | 2 | · | 2 | ||||
| 5 | = | 5 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
| 1 | = | 1 | ||||||||
| 4 | = | 2 | · | 2 | ||||||
| 5 | = | 5 | ||||||||
| LCM | = | 1 | · | 2 | · | 2 | · | 5 | = | 20 |
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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