How to find the Least Common Multiple of 15 and 20?
On this page below, we'll use the Prime Factorisation, and the List of Multiples method to find out the LCM of 15 and 20.
Follow the steps below, and let's calculate the LCM of 15 and 20.
Method 1 - Prime factorization
Step 1: Create a list of all the prime factors of the numbers 15 and 20:
Prime factors of 15
The prime factors of 15 are 3 and 5. Prime factorization of 15 in exponential form is:
15 = 31x51
Prime factors of 20
The prime factors of 20 are 2, 2 and 5. Prime factorization of 20 in exponential form is:
20 = 22x51
Step 2: Identify the highest power of each prime number from the above boxes:
31, 51, 22
Step 3: Multiply these values together:
31x51x22=60
Step 4: The result:
As seen on the calculation above, we have now obtained the LCM of 15 and 20.
The Least Common Multiple of 15 and 20 is 60.
Method 2 - List of Multiples
Find and list multiples of each number until the first common multiple is found. This is the lowest common multiple.
Multiples of 15:
15, 30, 45, 60, 75, 90, 105
Multiples of 20:
20, 40, 60, 80, 100, 120
Therefore,
LCM(15, 20) = 60