What is the least common multiple of 6 and 18?

Understand the Problem

The question is asking for the least common multiple (LCM) of the numbers 6 and 18. To find the LCM, we can use the prime factorization method or list the multiples of each number and identify the smallest common one.

Answer

$18$
Answer for screen readers

The least common multiple (LCM) of 6 and 18 is 18.

Steps to Solve

  1. Find the prime factorization of each number

To find the LCM using prime factorization, start by determining the prime factors of the numbers.

For 6: The prime factorization is $6 = 2 \times 3$.

For 18: The prime factorization is $18 = 2 \times 3^2$.

  1. Identify the highest power of each prime factor

Next, identify the highest power of all prime factors involved.

  • The prime factor 2 appears in both factorizations:

    • In 6, it appears as $2^1$.
    • In 18, it appears as $2^1$.
  • The prime factor 3 also appears in both:

    • In 6, it appears as $3^1$.
    • In 18, it appears as $3^2$.

Thus we take the highest power for each prime factor:

  • For 2, the highest power is $2^1$.
  • For 3, the highest power is $3^2$.
  1. Calculate the LCM

Now, multiply the highest powers of each prime factor to find the LCM:

$$ LCM = 2^1 \times 3^2 $$

Calculating this gives:

$$ LCM = 2 \times 9 = 18 $$

The least common multiple (LCM) of 6 and 18 is 18.

More Information

The least common multiple is the smallest number that is a multiple of both original numbers. In this case, 18 is the smallest number that can be divided by both 6 and 18 without leaving a remainder. It's also important to note that when one number is a multiple of another, the larger number is often the LCM.

Tips

  • Forgetting to list all prime factors: Always ensure to include all primes when factoring.
  • Confusing LCM with GCD: Remember that LCM looks for the smallest common multiple, while GCD (greatest common divisor) looks for the largest factor they share.

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