LCM( 7, 14, 20 ) = 140
Step 1: Write down factorisation of each number:
7 = 7
14 = 2 · 7
20 = 2 · 2 · 5
Step 2 : Match primes vertically:
7 | = | 7 | ||||||
14 | = | 2 | · | 7 | ||||
20 | = | 2 | · | 2 | · | 5 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
7 | = | 7 | ||||||||
14 | = | 2 | · | 7 | ||||||
20 | = | 2 | · | 2 | · | 5 | ||||
LCM | = | 2 | · | 2 | · | 5 | · | 7 | = | 140 |
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.