IXL | Least common denominator

What
is
the
least
common
denominator
of
7
10
and
2
5
?

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Learn with an example

question

What
is
the
least
common
denominator
of
5
6
and
1
12
?

key idea

The least common denominator is the least common multiple of the denominators.

solution

The denominators are 6 and 12. Find the least common multiple of 6 and 12.

Write the prime factorization for each number.

6 = 2 × 3
12 = 2 × 2 × 3

Repeat each prime factor the most number of times it appears in any of the prime factorizations above.

The most the factor 2 appears is twice.

The most the factor 3 appears is once.

So, multiply:

2 × 2 × 3 = 12

The least common multiple of 6 and 12 is 12.

The least common denominator of

5
6
and
1
12

is 12.

Looking for more? Try these:

Lesson: Least common denominator

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E.3Least common multiple

Lesson: Least common denominator

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