Denominators 2–12

20 denominators 2–12 problems with an answer key. Print with your browser; the answers print on a separate page.

Name: ____________________ Date: __________

3/5 − 1/2 = ______
3/4 − 1/2 = ______
4/11 − 1/11 = ______
3/9 − 1/8 = ______
1/3 − 1/4 = ______
9/11 − 5/7 = ______
4/5 − 4/8 = ______
8/12 − 3/5 = ______
9/10 − 1/2 = ______
2/3 − 5/11 = ______
2/7 − 1/9 = ______
6/7 − 1/2 = ______
6/10 − 1/6 = ______
4/11 − 1/5 = ______
8/12 − 1/2 = ______
3/4 − 4/7 = ______
6/9 − 3/9 = ______
5/11 − 1/10 = ______
1/2 − 2/8 = ______
9/12 − 2/3 = ______

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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: 3/5 − 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 5 and 2: it is 10.
Rewrite each fraction over 10: 3/5 = 6/10, 1/2 = 5/10.
Subtract the numerators: 6 − 5 = 1, giving 1/10.
1/10 is already in simplest form.

What this level practises

Denominators 2–12 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 subtracting fractions

Subtract the numerators and keep the denominator once the fractions have a common denominator.
If the second fraction is bigger, the answer is negative; the negative levels practise exactly this.
Rewrite with the lowest common multiple of the denominators so the numbers stay small.
Simplify the result, and check it by adding the second fraction back to the answer.

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

Answer key

3/5 − 1/2 = 1/10
3/4 − 1/2 = 1/4
4/11 − 1/11 = 3/11
3/9 − 1/8 = 5/24
1/3 − 1/4 = 1/12
9/11 − 5/7 = 8/77
4/5 − 4/8 = 3/10
8/12 − 3/5 = 1/15
9/10 − 1/2 = 2/5
2/3 − 5/11 = 7/33
2/7 − 1/9 = 11/63
6/7 − 1/2 = 5/14
6/10 − 1/6 = 13/30
4/11 − 1/5 = 9/55
8/12 − 1/2 = 1/6
3/4 − 4/7 = 5/28
6/9 − 3/9 = 1/3
5/11 − 1/10 = 39/110
1/2 − 2/8 = 1/4
9/12 − 2/3 = 1/12

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Questions

What grade is denominators 2–12 for?

It is usually taught in grade 5, but the right level is the one a child can finish with few mistakes. Move on when a sheet feels easy.

Can I print a different worksheet?

Yes. Press “New worksheet” for a fresh set of numbers at the same level; each set has its own answer key, so you can print as many as you need.

Are the answers checked?

The answers are worked out by the same program that makes the problems, so the key always matches the sheet. The worked example above shows the method.

How long should a worksheet take?

Most children finish 20 problems at a comfortable level in ten to fifteen minutes. If it takes much longer, try an easier level first.