Least Common Denominator (LCD) of 3, 9, and 20 The Least Common Denominator of 3, 9 and 20, also known as the Lowest Common Denominator of 3, 9 and 20, is useful if you need to add, subtract, or compare three fractions with the denominators of 3, 9 and 20.

The fractions with 3, 9 and 20 denominators will look like this:

 X 3

 Y 9

 Z 20

The Least Common Denominator of 3, 9 and 20 is 180.

You need to multiply 3 by 60, 9 by 20, and 20 by 9 to make them all 180. Furthermore, you need to multiply the numerators by the same amounts to keep the fraction values the same.

Therefore, you have to make the following calculations so the fractions keep the same value and get the same denominator:

 X x 60 3 x 60

 Y x 20 9 x 20

 Z x 9 20 x 9

Which gives you the following three new fractions that you can add, subtract and compare:

 60X 180

 20Y 180

 9Z 180

You can substitute X, Y and Z with the numerators of your fractions with 3, 9 and 20 denominators. This way you can add, subtract and compare your fractions correctly.

Least Common Denominator Calculator
Please enter another two or three denominators below so we can calculate the Least Common Denominator (LCD) for you:

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Least Common Denominator (LCD) of 3, 9 and 21
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Notes

The Least Common Denominator of 3, 9 and 20 is the same as the Least Common Multiple of 3, 9 and 20.

To calculate what to multiply each denominator and corresponding numerator by, we divided the LCD by each of the denominators.