LCM( 7, 14, 12, 4 ) = 84
Step 1: Write down factorisation of each number:
7 = 7
14 = 2 · 7
12 = 2 · 2 · 3
4 = 2 · 2
Step 2 : Match primes vertically:
7 | = | 7 | ||||||
14 | = | 2 | · | 7 | ||||
12 | = | 2 | · | 2 | · | 3 | ||
4 | = | 2 | · | 2 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
7 | = | 7 | ||||||||
14 | = | 2 | · | 7 | ||||||
12 | = | 2 | · | 2 | · | 3 | ||||
4 | = | 2 | · | 2 | ||||||
LCM | = | 2 | · | 2 | · | 3 | · | 7 | = | 84 |