Least Common Denominator (LCD) of 21, 40, and 87
The Least Common Denominator of 21, 40 and 87, also known as the Lowest Common Denominator of 21, 40 and 87, is useful if you need to add, subtract, or compare three fractions with the denominators of 21, 40 and 87.
The fractions with 21, 40 and 87 denominators will look like this:
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The Least Common Denominator of 21, 40 and 87 is 24360.
You need to multiply 21 by 1160, 40 by 609, and 87 by 280 to make them all 24360. 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:
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Which gives you the following three new fractions that you can add, subtract and compare:
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You can substitute X, Y and Z with the numerators of your fractions with 21, 40 and 87 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:
Least Common Denominator (LCD) of 21, 40 and 88
Here is the next set of numbers we have calculated the LCD for.
Notes
The Least Common Denominator of 21, 40 and 87 is the same as the Least Common Multiple of 21, 40 and 87.
To calculate what to multiply each denominator and corresponding numerator by, we divided the LCD by each of the denominators.