LCM( 30, 42 ) = 210
Step 1: Write down factorisation of each number:
30 = 2 · 3 · 5
42 = 2 · 3 · 7
Step 2 : Match primes vertically:
30 | = | 2 | · | 3 | · | 5 | ||
42 | = | 2 | · | 3 | · | 7 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
30 | = | 2 | · | 3 | · | 5 | ||||
42 | = | 2 | · | 3 | · | 7 | ||||
LCM | = | 2 | · | 3 | · | 5 | · | 7 | = | 210 |
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.