What is the least common multiple of 30 and 8?

Understand the Problem

The question is asking for the least common multiple (LCM) of the numbers 30 and 8. To find the LCM, we will identify the prime factors of each number and then use those prime factors to calculate the LCM.

Answer

120
Answer for screen readers

The least common multiple (LCM) of 30 and 8 is 120.

Steps to Solve

  1. Identify the Prime Factors of Each Number

First, we'll find the prime factors of 30 and 8.

  • The prime factors of 30 are: $$ 30 = 2 \times 3 \times 5 $$

  • The prime factors of 8 are: $$ 8 = 2^3 $$

  1. List All Unique Prime Factors

Next, we need to list all unique prime factors from both numbers.

  • The unique prime factors are: $$ 2, 3, 5 $$
  1. Determine the Highest Power of Each Prime Factor

Now we find the highest power of each prime factor present in either number:

  • For the prime factor 2, the highest power is (2^3) (from 8).
  • For the prime factor 3, the highest power is (3^1) (from 30).
  • For the prime factor 5, the highest power is (5^1) (from 30).
  1. Calculate the LCM

Finally, we multiply the highest powers of all prime factors to get the least common multiple:

$$ \text{LCM} = 2^3 \times 3^1 \times 5^1 $$

Calculating this gives:

$$ \text{LCM} = 8 \times 3 \times 5 $$

  1. Finalize the Multiplication

Now we perform the multiplication step-by-step:

First, calculate (8 \times 3):

$$ 8 \times 3 = 24 $$

Then multiply it by 5:

$$ 24 \times 5 = 120 $$

Thus,

$$ \text{LCM}(30, 8) = 120 $$

The least common multiple (LCM) of 30 and 8 is 120.

More Information

The least common multiple (LCM) is useful in various applications such as solving problems involving fractions or finding timings in events that repeat at different intervals. The LCM helps in ensuring that we find a common time or space where the conditions overlap.

Tips

  • Forgetting to include the highest power for prime factors that appear more than once (like 2 in this case).
  • Mixing up the multiplication order can also lead to mistakes, so make sure to follow through calculations step by step.
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