LCM( 3, 6, 9, 12 ) = 36
Step 1: Write down factorisation of each number:
3 = 3
6 = 2 · 3
9 = 3 · 3
12 = 2 · 2 · 3
Step 2 : Match primes vertically:
| 3 | = | 3 | ||||||
| 6 | = | 2 | · | 3 | ||||
| 9 | = | 3 | · | 3 | ||||
| 12 | = | 2 | · | 2 | · | 3 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
| 3 | = | 3 | ||||||||
| 6 | = | 2 | · | 3 | ||||||
| 9 | = | 3 | · | 3 | ||||||
| 12 | = | 2 | · | 2 | · | 3 | ||||
| LCM | = | 2 | · | 2 | · | 3 | · | 3 | = | 36 |