Question
Find Least Common Multiple of 12, 15, 16, 20 and 25 using prime factorisation method.
Answer
LCM( 12, 15, 16, 20, 25 ) = 1200
Explanation
Step 1: Write down factorisation of each number:
12 = 2 · 2 · 3
15 = 3 · 5
16 = 2 · 2 · 2 · 2
20 = 2 · 2 · 5
25 = 5 · 5
Step 2 : Match primes vertically:
| 12 | = | 2 | · | 2 | · | 3 | ||||||||
| 15 | = | 3 | · | 5 | ||||||||||
| 16 | = | 2 | · | 2 | · | 2 | · | 2 | ||||||
| 20 | = | 2 | · | 2 | · | 5 | ||||||||
| 25 | = | 5 | · | 5 |
Step 3 : Bring down numbers in each column and multiply to get LCM:
| 12 | = | 2 | · | 2 | · | 3 | ||||||||||
| 15 | = | 3 | · | 5 | ||||||||||||
| 16 | = | 2 | · | 2 | · | 2 | · | 2 | ||||||||
| 20 | = | 2 | · | 2 | · | 5 | ||||||||||
| 25 | = | 5 | · | 5 | ||||||||||||
| LCM | = | 2 | · | 2 | · | 2 | · | 2 | · | 3 | · | 5 | · | 5 | = | 1200 |
This page was created using
LCM Calculator