LCM( 4, 9, 12, 10 ) = 180
Step 1: Write down factorisation of each number:
4 = 2 · 2
9 = 3 · 3
12 = 2 · 2 · 3
10 = 2 · 5
Step 2 : Match primes vertically:
| 4 | = | 2 | · | 2 | ||||||
| 9 | = | 3 | · | 3 | ||||||
| 12 | = | 2 | · | 2 | · | 3 | ||||
| 10 | = | 2 | · | 5 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
| 4 | = | 2 | · | 2 | ||||||||
| 9 | = | 3 | · | 3 | ||||||||
| 12 | = | 2 | · | 2 | · | 3 | ||||||
| 10 | = | 2 | · | 5 | ||||||||
| LCM | = | 2 | · | 2 | · | 3 | · | 3 | · | 5 | = | 180 |