Adding Fractions (Same Denominator)
Add and subtract fractions with the same denominator, including results greater than one whole (e.g. 5/8 + 6/8 = 11/8)
What a learner can do afterwards
- Calculate 3/5 + 4/5 = 7/5 and explain it equals 1 2/5
- Subtract 2/6 from 5/6
- Solve addition problems where the sum exceeds the whole: 7/8 + 3/8
The lesson
When fractions have the same bottom number, adding them is easy: add the top numbers and keep the bottom number the same. Subtracting works the same way. You subtract the top numbers and keep the bottom number the same.
Mia has 5/6 of a ribbon. She cuts off 2/6 for a bow. Subtract the top numbers: 5 - 2 = 3. The bottom number stays 6, so 3/6 of the ribbon is left.
Sometimes adding fractions gives a top number bigger than the bottom number. Try 3/5 + 4/5. Add the top numbers: 3 + 4 = 7, so the answer is 7/5. Since 7 is bigger than 5, this is more than one whole. Five fifths make one whole, so 7/5 is 1 whole with 2/5 left over: 1 2/5.
A common mistake is adding or subtracting the bottom numbers too. Keep the bottom number the same the whole time. Only the top numbers change.
Add or subtract only the top numbers, keep the bottom number the same, and rewrite the answer as a mixed number when the top number passes the bottom.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.