Quick answer

You can add fractions with unlike denominators by rewriting them with a common denominator first.

Find a common denominator

For 1/3 + 1/4, 12 is a common denominator because both 3 and 4 divide into 12.

Rewrite each fraction

1/3 = 4/12 and 1/4 = 3/12. Now add the numerators: 4/12 + 3/12 = 7/12.

Simplify if possible

For 1/6 + 1/3, rewrite 1/3 as 2/6. The sum is 3/6 = 1/2.

Worked examples

  • 1/2 + 1/4 = 3/4
  • 1/3 + 1/6 = 1/2
  • 2/5 + 1/10 = 1/2

Common mistake to avoid

Never add denominators directly: 1/2 + 1/3 is not 2/5.

Practice questions

Try these without looking at the answers first. Explain your reasoning aloud or write each step.

  • Question: 1/4 + 1/4 — Answer: 1/2
  • Question: 1/2 + 1/3 — Answer: 5/6
  • Question: 1/8 + 3/8 — Answer: 1/2

What to learn next

Review the related lessons linked below, then practice independently. If you make an error, write down which rule you used and why it did not apply.

Explore FitGitt practice.