LCM( 3, 7, 9 ) = 63
Step 1: Write down factorisation of each number:
3 = 3
7 = 7
9 = 3 · 3
Step 2 : Match primes vertically:
3 | = | 3 | ||||
7 | = | 7 | ||||
9 | = | 3 | · | 3 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
3 | = | 3 | ||||||
7 | = | 7 | ||||||
9 | = | 3 | · | 3 | ||||
LCM | = | 3 | · | 3 | · | 7 | = | 63 |
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.