How to Add Fractions with Unlike Denominators
Learn to find a common denominator, rewrite each fraction, then add. Follow the worked examples, then try it yourself.
See It
Study the worked examples below. Each step is shown so you can follow exactly how the problem is solved.
Do It
Now it's your turn. Grab a pencil and paper and try these problems using the method you just studied.
Check It
Done? Reveal the answer key to check your work.
What Does It Mean to Add Fractions with Unlike Denominators?
When two fractions have different denominators — like 1/3 and 1/4 — you can't add them directly because the pieces are different sizes. You first need to rewrite both fractions so they share a common denominator.
To find a common denominator, look for the least common multiple (LCM) of the two denominators. Then multiply each fraction's numerator and denominator by whatever factor makes its denominator equal to the LCM. Once both fractions have the same denominator, simply add the numerators.
Adding fractions with unlike denominators is one of the most important fraction skills. It appears constantly in math — from recipe conversions to algebra — so building a strong foundation here pays off for years to come.
This Is One Activity From Book 2: Fractions
The full book has 40 activities just like this one — each with worked examples, matching practice problems, and a complete answer key. No tutor needed. No app. Just a pencil and a workbook.
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