LCM( 2, 3, 4, 5, 7 ) = 420
Step 1: Write down factorisation of each number:
2 = 2
3 = 3
4 = 2 · 2
5 = 5
7 = 7
Step 2 : Match primes vertically:
2 | = | 2 | ||||||||
3 | = | 3 | ||||||||
4 | = | 2 | · | 2 | ||||||
5 | = | 5 | ||||||||
7 | = | 7 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
2 | = | 2 | ||||||||||
3 | = | 3 | ||||||||||
4 | = | 2 | · | 2 | ||||||||
5 | = | 5 | ||||||||||
7 | = | 7 | ||||||||||
LCM | = | 2 | · | 2 | · | 3 | · | 5 | · | 7 | = | 420 |