Video: Adding Three Proper Fractions of the Same Denominator

Determine the sum of 4/13, 3/13, and 8/13.

02:08

Video Transcript

Determine the sum of four 13ths, three 13ths, and eight 13ths.

The first thing we notice is the word “sum.” And we remember that that means we’re going to be adding these fractions. And when we add fractions, the first step is to find a common denominator. The three fractions we’re given, four 13ths, three 13ths, and eight 13ths, already have a common denominator. If the denominators are the same, the next step would be add the numerators together.

We copy down the three fractions and add the numerators, four plus three plus eight, which equals 15. And when adding fractions, the denominator doesn’t change. So we have 15 over 13, 15 13ths.

However, the final step here is always to simplify. Can we simplify or reduce 15 13ths? We can break 15 13ths into two pieces: 13 13ths plus two 13ths. Saying 13 over 13 is the same thing as saying one. So 13 13ths simplifies to one. Two 13ths cannot be simplified any further. Our fraction, 15 13ths, can be simplified to a mixed number, one and two 13ths. The final answer here is one and two 13ths.

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