Adding and Subtracting Fractions Worksheets

Adding and subtracting fractions worksheets focus on the hardest part of fraction arithmetic: unlike denominators. Students find a common denominator, rewrite each fraction, and then add or subtract the numerators. These free printable worksheets cover fractions with unlike denominators and mixed numbers, with an answer key on every PDF and a maker for new problems.

Quick answer: To add or subtract fractions with unlike denominators, find a common denominator, rewrite each fraction with it, then add or subtract the numerators and simplify: 1/2 + 1/3 = 3/6 + 2/6 = 5/6. This page has 4 free adding and subtracting fractions worksheets (PDF) with answer keys, plus a maker for new problems. Updated October 2026.

Ready-to-print samples

A few of the ready PDFs on this page. The full list is under Ready-to-print worksheets, and the maker above makes new problems on demand.

How to add and subtract fractions with unlike denominators

1. Find the least common denominator (LCD): the smallest number that both denominators divide into.
2. Rewrite each fraction with the LCD, multiplying the numerator by the same number as the denominator.
3. Add or subtract the numerators and keep the denominator.
4. Simplify the answer, or write it as a mixed number.

Least common denominators for common pairs

A quick way to find the LCD is to list multiples of the larger denominator until the smaller one divides into it. This table shows six pairs that appear again and again:

Adding and subtracting fractions: six worked examples

Each row shows the fractions rewritten with the LCD, the sum or difference of the numerators and the answer in simplest form:

Adding mixed numbers worksheet and subtracting mixed numbers

For mixed numbers, change each one to an improper fraction, add or subtract, and change the answer back. Three examples:

Adding fractions worksheet, subtracting fractions worksheet and unlike denominators worksheet

This page is also searched as adding fractions worksheet, subtracting fractions worksheet, adding fractions with unlike denominators worksheet, subtracting fractions with unlike denominators, add and subtract fractions and unlike denominators worksheet. All of them are the free PDFs above, each with an answer key, for US Letter or A4, with no sign-up. For fractions with the same denominator, see the fractions worksheets page first.

Common Core standards for adding and subtracting fractions

These worksheets practice the Common Core fractions standards for grades 4 and 5:

Common mistakes when adding and subtracting fractions

A weekly plan for adding and subtracting fractions

Try ten adding and subtracting fractions problems

Use this set as a warm-up or a quick check. Find the least common denominator first, rewrite both fractions, then add or subtract. Answers are in simplest form.

Why you need a common denominator

You can only add or subtract pieces that are the same size. Halves and thirds are different sizes, so 1/2 + 1/3 cannot be written as a count of anything until both are cut into sixths. That is what the common denominator does: it rewrites both fractions in pieces of the same size, so the numerators can be counted together.

Any common multiple of the denominators works, but the least common denominator keeps the numbers small and often removes the need to simplify at the end. For 3/4 + 5/6, the LCD is 12, giving 9/12 + 10/12 = 19/12, which is 1 7/12. Using 24 would also work, but the answer would need simplifying.

Adding and subtracting fractions vocabulary

Students answer questions faster when they know the words. These are the terms used on the worksheets and answer keys:

Real-life uses of adding and subtracting fractions

Anyone who cooks, builds or measures adds and subtracts fractions with unlike denominators. Some everyday cases:

Tips for teachers and parents

Before any rule, build equivalent fractions with strips or a number line so children can see that 1/2 and 3/6 are the same length. Then introduce the least common denominator as the first place the two fraction strips line up.

Have students estimate with benchmark fractions, as standard 5.NF.A.2 asks: 5/8 is a little more than 1/2, and 1/3 is a little less, so the sum should be a bit more than 1. A quick estimate catches the most common mistake, adding the denominators.

Which adding and subtracting fractions worksheet should you start with?

If students can already find a common denominator, start at level 6 and move to mixed numbers once they score above 90 percent. For children who need more help, begin with equivalent fractions and fractions with like denominators.

More math practice

• Multiplying fractions worksheets.
• Dividing fractions worksheets.
• The fraction calculator and the fraction strips.