LCM( 2, 1, 3, 3, 1, 5, 9 ) = 90
Step 1: Write down factorisation of each number:
2 = 2
1 = 1
3 = 3
3 = 3
1 = 1
5 = 5
9 = 3 · 3
Step 2 : Match primes vertically:
2 | = | 2 | ||||||||
1 | = | 1 | ||||||||
3 | = | 3 | ||||||||
5 | = | 5 | ||||||||
9 | = | 3 | · | 3 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
2 | = | 2 | ||||||||||
1 | = | 1 | ||||||||||
3 | = | 3 | ||||||||||
5 | = | 5 | ||||||||||
9 | = | 3 | · | 3 | ||||||||
LCM | = | 1 | · | 2 | · | 3 | · | 3 | · | 5 | = | 90 |