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How do you find the LCM of 15, 20?

Answer 1

Autumn Arnold

60

method 1

Until the lowest common number is found, write out the multiples of both numbers.

multiples 15:#" "{15,30, 45,color(blue)60,75,90,105,color(blue)120,135,...}#

multiples 20:#" "{20,40,color(blue)60, 80,100,color(blue)120,...}#

#LCM(15,20)=60#

method 2

use #hcfxxlcm=axxb#

#hcf=gcm(15,20)=5#

so#" "5xxlcm=15xx20#

#lcm=(15xx20)/5#

Easier to cancel before evaluating.

#lcm=(cancel(15)^3xx20)/cancel(5)=60#

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Answer 2

Benjamin Altschul

To find the least common multiple (LCM) of 15 and 20, follow these steps:

Factor each number into its prime factors:
- 15 = (3 \times 5)
- 20 = (2^2 \times 5)
Identify all the unique prime factors present in both numbers. Include each factor the maximum number of times it occurs in any one of the numbers.
- (2^2), (3), and (5)
Multiply all the prime factors obtained in step 2.
- LCM = (2^2 \times 3 \times 5)
Calculate the product:
- LCM = (4 \times 3 \times 5)
- LCM = 60

Therefore, the least common multiple of 15 and 20 is 60.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.