LCM( 3, 9, 12 ) = 36
Step 1: Write down factorisation of each number:
3 = 3
9 = 3 · 3
12 = 2 · 2 · 3
Step 2 : Match primes vertically:
3 | = | 3 | ||||||
9 | = | 3 | · | 3 | ||||
12 | = | 2 | · | 2 | · | 3 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
3 | = | 3 | ||||||||
9 | = | 3 | · | 3 | ||||||
12 | = | 2 | · | 2 | · | 3 | ||||
LCM | = | 2 | · | 2 | · | 3 | · | 3 | = | 36 |
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.