Definition of

Least Common Denominator

Least Common Denominator
The smallest number that can be used for all denominators of 2 or more fractions:

• a "Denominator" is the bottom number of a fraction.
• a "Common Denominator" is when the bottom number is the same for the fractions
• the "Least Common Denominator" is the smallest number that can be used for all denominators of the fractions

Example: the Least Common Denominator of 1/2 and 2/3
1/2 can also be written as 2/4, or 3/6, or 4/8, etc
2/3 can also be written as 4/6, or 6/9, or 8/12, etc
Looking at those lists we can see that 3/6 and 4/6 have the same denominator, and it is the smallest such denominator
So the Least Common Denominator of 1/2 and 2/3 is 6


It makes it easy to add and subtract the fractions.

Example: to add 1/2 and 2/3 we can use the Least Common Denominator of 6:
3/6 + 4/6 = 7/6

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