LCM( 4, 7, 9 ) = 252
Step 1: Write down factorisation of each number:
4 = 2 · 2
7 = 7
9 = 3 · 3
Step 2 : Match primes vertically:
4 | = | 2 | · | 2 | ||||||
7 | = | 7 | ||||||||
9 | = | 3 | · | 3 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
4 | = | 2 | · | 2 | ||||||||
7 | = | 7 | ||||||||||
9 | = | 3 | · | 3 | ||||||||
LCM | = | 2 | · | 2 | · | 3 | · | 3 | · | 7 | = | 252 |
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.