How to find the Least Common Multiple of 8 and 21?
On this page below, we'll use the Prime Factorisation, and the List of Multiples method to find out the LCM of 8 and 21.
Follow the steps below, and let's calculate the LCM of 8 and 21.
Method 1 - Prime factorization
Step 1: Create a list of all the prime factors of the numbers 8 and 21:
Prime factors of 8
The prime factors of 8 are 2, 2 and 2. Prime factorization of 8 in exponential form is:
8 = 23
Prime factors of 21
The prime factors of 21 are 3 and 7. Prime factorization of 21 in exponential form is:
21 = 31x71
Step 2: Identify the highest power of each prime number from the above boxes:
23, 31, 71
Step 3: Multiply these values together:
23x31x71=168
Step 4: The result:
As seen on the calculation above, we have now obtained the LCM of 8 and 21.
The Least Common Multiple of 8 and 21 is 168.
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 8:
8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, 128, 136, 144, 152, 160, 168, 176, 184, 192
Multiples of 21:
21, 42, 63, 84, 105, 126, 147, 168, 189, 210, 231
Therefore,
LCM(8, 21) = 168