Finding HCF & LCM with Prime Factorizations
We want to find the HCF and LCM of the numbers 60 and 72.
Start by writing each number as a product of its prime factors.
60 = 2 * 2 * 3 * 5 |
72 = 2 * 2 * 2 * 3 * 3 |
60 | = 2 | * 2 | * 3 | * 5 | ||
72 | = 2 | * 2 | * 2 | * 3 | * 3 |
appear in both lists:
So the HCF of 60 and 72 is 2 × 2 × 3 which is 12.
The lowest common multiple is found by multiplying all the factors which appear in either
list:
So the LCM of 60 and 72 is 2 × 2 × 2 × 3 × 3 × 5 which is 360.
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