LCM( 12, 15, 21, 27 ) = 3780
Step 1: Write down factorisation of each number:
12 = 2 · 2 · 3
15 = 3 · 5
21 = 3 · 7
27 = 3 · 3 · 3
Step 2 : Match primes vertically:
12 | = | 2 | · | 2 | · | 3 | ||||||||
15 | = | 3 | · | 5 | ||||||||||
21 | = | 3 | · | 7 | ||||||||||
27 | = | 3 | · | 3 | · | 3 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
12 | = | 2 | · | 2 | · | 3 | ||||||||||
15 | = | 3 | · | 5 | ||||||||||||
21 | = | 3 | · | 7 | ||||||||||||
27 | = | 3 | · | 3 | · | 3 | ||||||||||
LCM | = | 2 | · | 2 | · | 3 | · | 3 | · | 3 | · | 5 | · | 7 | = | 3780 |