Adding and subtracting fractions with different denominators

Mathematics · Fractions · ages 10-11

Name ______________________ Date ____________

Add 1/2 + 1/6 using sixths. What is the numerator before simplifying?
Answer: ______________
What is 1/3 + 1/4?
- 2/7
- 7/12
- 5/12
- 1/2
What do you need to do before adding 1/4 + 1/6?
- Add the two denominators
- Find a common denominator
- Add the two numerators now
To add 2/5 + 1/3, you can add the numerators and add the denominators separately.
Circle one: True False
Find 2 1/3 - 1 1/6. Write the result as one fraction with denominator 6, not as a mixed number. What is its numerator?
Answer: ______________
What is the least common denominator of the fraction parts in 2 1/4 and 1 2/5?
Answer: ______________
What is 3/5 + 1/4?
- 4/9
- 13/20
- 17/20
- 3/4
Aisha's sum, 1/6 + 3/4 = 11/12, is correct.
Circle one: True False
What does 1 3/5 become when written as one fraction with denominator 20?
- 30/20
- 34/20
- 32/20
What is 7/8 + 5/6?
- 41/24
- 12/14
- 31/24
- 35/48

Answer key

For grown-ups. Fold this page away before handing over the rest.

4 · 1/2 = 3/6, so the total is 4/6.
7/12 · Four twelfths and three twelfths make seven twelfths.
Find a common denominator · Fractions need matching denominators before you can add the numerators.
False · That gives the wrong size pieces. You must convert both fractions to a common denominator first.
7 · 2 1/3 = 14/6 and 1 1/6 = 7/6. Subtracting gives the single fraction 7/6, whose numerator is 7.
20 · The first positive multiple shared by 4 and 5 is 20.
17/20 · 3/5 = 12/20 and 1/4 = 5/20. Their sum is 17/20.
True · Two twelfths and nine twelfths make eleven twelfths.
32/20 · One whole is five fifths. Add three fifths to get 8/5, then multiply both numbers by four to get 32/20.
41/24 · 7/8 = 21/24 and 5/6 = 20/24, so their sum is 41/24.