20 denominators 2–10 problems with an answer key. Print with your browser; the answers print on a separate page.
How to use this worksheet
Print it, set a time limit if you like, and mark it with the key. Press “New worksheet” for a fresh set of numbers at the same level: every set is different, so it works for repeated practice and for a whole class.
Worked example: 2/4 + 1/2
Here is the method for the first problem on this sheet, step by step. The same steps work for every problem at this level.
- The denominators are different. Find the lowest common multiple of 4 and 2: it is 4.
- Rewrite each fraction over 4: 2/4 = 2/4, 1/2 = 2/4.
- Add the numerators: 2 + 2 = 4, giving 4/4.
- Simplify by dividing the top and bottom by 4: the answer is 1.
What this level practises
Denominators 2–10 is usually taught in grade 5. This sheet has 20 problems, and every answer is given in simplest form. Work through the sheet without a calculator, then mark it with the key: the aim is accuracy first and speed second.
Tips for adding fractions
- Only the numerators are added; the denominator says what size the pieces are and stays the same.
- With different denominators, rewrite the fractions with a common denominator first. The lowest common multiple keeps the numbers small.
- Simplify the answer by dividing the top and bottom by their greatest common factor.
- Drawing the fractions as bars or circles helps children see why the pieces must be the same size before adding.
Printing
Use your browser’s print command. The menus, buttons and ads are left off the printout, and the answer key starts on a new page so it can be kept back. For a whole class, print one sheet, press “New worksheet” and print again to give each group different numbers.
Other levels