Understanding fractions
Lesson 2 of 11
Adding and subtracting fractions
Objective. Add and subtract fractions with different denominators.
The key idea
You can only add slices of the same size, so rewrite both fractions over a common denominator first.
Worked example
Calculate 2/3 + 1/4.
- 1Common denominator is 12.
- 22/3 = 8/12 and 1/4 = 3/12.
- 38/12 + 3/12 = 11/12.
Answer: 11/12
Practice
Each question comes with a picture and a listen button. Try it first, then reveal the answer.
Common mistake. Adding denominators together. 1/2 + 1/2 is 1, not 2/4.
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