LCM( 4, 8, 3, 9 ) = 72
Step 1: Write down factorisation of each number:
4 = 2 · 2
8 = 2 · 2 · 2
3 = 3
9 = 3 · 3
Step 2 : Match primes vertically:
| 4 | = | 2 | · | 2 | ||||||
| 8 | = | 2 | · | 2 | · | 2 | ||||
| 3 | = | 3 | ||||||||
| 9 | = | 3 | · | 3 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
| 4 | = | 2 | · | 2 | ||||||||
| 8 | = | 2 | · | 2 | · | 2 | ||||||
| 3 | = | 3 | ||||||||||
| 9 | = | 3 | · | 3 | ||||||||
| LCM | = | 2 | · | 2 | · | 2 | · | 3 | · | 3 | = | 72 |