LCM( 20, 28, 35, 32 ) = 1120
Step 1: Write down factorisation of each number:
20 = 2 · 2 · 5
28 = 2 · 2 · 7
35 = 5 · 7
32 = 2 · 2 · 2 · 2 · 2
Step 2 : Match primes vertically:
20 | = | 2 | · | 2 | · | 5 | ||||||||
28 | = | 2 | · | 2 | · | 7 | ||||||||
35 | = | 5 | · | 7 | ||||||||||
32 | = | 2 | · | 2 | · | 2 | · | 2 | · | 2 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
20 | = | 2 | · | 2 | · | 5 | ||||||||||
28 | = | 2 | · | 2 | · | 7 | ||||||||||
35 | = | 5 | · | 7 | ||||||||||||
32 | = | 2 | · | 2 | · | 2 | · | 2 | · | 2 | ||||||
LCM | = | 2 | · | 2 | · | 2 | · | 2 | · | 2 | · | 5 | · | 7 | = | 1120 |