LCM( 3, 5, 9, 5, 15 ) = 45
Step 1: Write down factorisation of each number:
3 = 3
5 = 5
9 = 3 · 3
5 = 5
15 = 3 · 5
Step 2 : Match primes vertically:
3 | = | 3 | ||||
5 | = | 5 | ||||
9 | = | 3 | · | 3 | ||
15 | = | 3 | · | 5 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
3 | = | 3 | ||||||
5 | = | 5 | ||||||
9 | = | 3 | · | 3 | ||||
15 | = | 3 | · | 5 | ||||
LCM | = | 3 | · | 3 | · | 5 | = | 45 |