Worked example 1
Add 1/4 + 2/3.
Find the common denominator first. LCM of 4 and 3 is 12. Rewrite: 1/4 = 3/12 and 2/3 = 8/12. Now add: 3/12 + 8/12 = 11/12. Already in simplest form.
Answer: 11/12
Grade 6 Math · Topic 10
Adding Fractions with Unlike Denominators
You can only add fractions when they share the same denominator. When denominators are different, rewrite each fraction with a common denominator first — usually the least common multiple (LCM) — then add the numerators and keep the denominator the same.
Lesson alignment: Prerequisite review · 5.NF.A.1–2 · Take your time. You can return to this lesson whenever you need it.
Explore visually
Add fractions with a common-unit model
Rename both fractions with the same-sized pieces, then combine the numerators.
Think first: What common denominator could rename both fractions without changing their value?
Ready? Reveal the model and try your prediction
Swipe horizontally to see the full diagram.
Turn on JavaScript to adjust this model. The examples and practice below work without it.
Follow the worked examples
Read each step, then cover the explanation and see if you can explain why it works.
Worked example 2
Add 5/6 + 3/8.
Find the common denominator first. LCM of 6 and 8 is 24. Rewrite: 5/6 = 20/24 and 3/8 = 9/24. Now add: 20/24 + 9/24 = 29/24 = 1 5/24.
Answer: 1 5/24
Try a few on your own
Work these on paper first. Open “Check” when you are ready to compare your answer.
- 1/2 + 1/3 =
Check
5/6
- 2/5 + 1/4 =
Check
13/20
- 3/8 + 1/6 =
Check
13/24
- 5/6 + 1/4 =
Check
1 1/12
- 2/9 + 1/3 =
Check
5/9
- 3/4 + 2/5 =
Check
1 3/20
- 7/10 + 1/2 =
Check
1 1/5
- 5/12 + 1/3 =
Check
3/4
Try this situation 1
Sara walked 2/3 of a mile in the morning and 1/4 of a mile in the afternoon. How far did she walk in total?
Show a worked solution
Answer: 11/12 mile.
Make the denominators match first. LCD is 12. 2/3 = 8/12, 1/4 = 3/12. Total: 8/12 + 3/12 = 11/12.
Try this situation 2
A recipe needs 3/4 cup of brown sugar and 2/3 cup of white sugar. How much sugar in total?
Show a worked solution
Answer: 1 5/12 cups.
Make the denominators match first. LCD is 12. 3/4 = 9/12, 2/3 = 8/12. Sum = 17/12 = 1 5/12.
Fresh questions · saved on this device
Practice this skill
Try a fresh set each time. Answer one question, check your thinking, and read the explanation. If you miss one, return to the visual model and try another round.
Question 1 of 50 correct so far
Session complete
Check what you learned
Answer these five questions on your own. You can review the explanations after you submit and try again whenever you like. This short check is for practice, not a grade.
Practice and finish
Try the linked topic quiz for more practice. If something is tricky, return to the example and look for the step that changes the numbers or representation.
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More Grade 6 resources
Use these free materials if you want another explanation, extra paper practice, or a broader review.