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How do you find the lowest common multiple of prime factors?

Published in Mathematics 2 mins read

To find the Lowest Common Multiple (LCM) using prime factorization, follow these steps:

  1. Find the Prime Factorization: Determine the prime factorization of each number you want to find the LCM for. This means breaking down each number into a product of its prime factors.

  2. List Prime Factors with Highest Powers: For each prime factor that appears in any of the factorizations, list it with the highest power to which it appears in any of the individual prime factorizations.

  3. Multiply: Multiply all the prime factors (with their highest powers) listed in the previous step. The result is the LCM.

Here's an example to illustrate the process:

Example: Find the LCM of 12 and 18.

  1. Prime Factorization:

    • 12 = 2 x 2 x 3 = 22 x 3
    • 18 = 2 x 3 x 3 = 2 x 32
  2. List Prime Factors with Highest Powers:

    • The prime factors are 2 and 3.
    • The highest power of 2 is 22.
    • The highest power of 3 is 32.
  3. Multiply:

    • LCM = 22 x 32 = 4 x 9 = 36

Therefore, the LCM of 12 and 18 is 36.

In essence: Prime factorization allows you to identify all the necessary prime components to construct a multiple common to all the original numbers, ensuring you choose the lowest such multiple by considering only the highest required power of each prime.

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