Grade 6 math worksheet for adding mixed numbers.

Let’s solve each problem step by step. We’re adding mixed numbers — that means a whole number plus a fraction. To add them, we can:

1. Add the whole numbers together.
2. Add the fractions together (if they have different denominators, find a common denominator first).
3. If the fraction part adds up to more than 1, turn it into a mixed number and add the whole number part to the total.

We’ll go one by one.

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Problem 1: 3 4/5 + 7 5/11

Whole numbers: 3 + 7 = 10

Fractions: 4/5 + 5/11
Find common denominator of 5 and 11 → 55
4/5 = (4×11)/(5×11) = 44/55
5/11 = (5×5)/(11×5) = 25/55
Add: 44/55 + 25/55 = 69/55
69/55 is more than 1 → 69 ÷ 55 = 1 with remainder 14 → so 1 14/55

Now add to whole number: 10 + 1 = 11, plus 14/55 → 11 14/55

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Problem 2: 4 10/12 + 6 2/8

First, simplify fractions if possible:
10/12 = 5/6
2/8 = 1/4

So now: 4 5/6 + 6 1/4

Whole numbers: 4 + 6 = 10

Fractions: 5/6 + 1/4
Common denominator of 6 and 4 → 12
5/6 = 10/12
1/4 = 3/12
Add: 10/12 + 3/12 = 13/12 = 1 1/12

Total: 10 + 1 = 11, plus 1/12 → 11 1/12

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Problem 3: 17 3/4 + 13 1/3

Whole numbers: 17 + 13 = 30

Fractions: 3/4 + 1/3
Common denominator: 12
3/4 = 9/12
1/3 = 4/12
Add: 9/12 + 4/12 = 13/12 = 1 1/12

Total: 30 + 1 = 31, plus 1/12 → 31 1/12

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Problem 4: 15 2/12 + 16 3/11

Simplify 2/12 = 1/6

So: 15 1/6 + 16 3/11

Whole numbers: 15 + 16 = 31

Fractions: 1/6 + 3/11
Common denominator: 66
1/6 = 11/66
3/11 = 18/66
Add: 11/66 + 18/66 = 29/66

No simplification needed → 31 29/66

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Problem 5: 20 2/3 + 14 1/8

Whole numbers: 20 + 14 = 34

Fractions: 2/3 + 1/8
Common denominator: 24
2/3 = 16/24
1/8 = 3/24
Add: 16/24 + 3/24 = 19/24

→ 34 19/24

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Problem 6: 18 2/6 + 8 2/7

Simplify 2/6 = 1/3

So: 18 1/3 + 8 2/7

Whole numbers: 18 + 8 = 26

Fractions: 1/3 + 2/7
Common denominator: 21
1/3 = 7/21
2/7 = 6/21
Add: 7/21 + 6/21 = 13/21

→ 26 13/21

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Problem 7: 3 2/10 + 8 8/10

Note: same denominator!

Whole numbers: 3 + 8 = 11

Fractions: 2/10 + 8/10 = 10/10 = 1

Total: 11 + 1 = 12

(You could also write as 12 0/10, but just 12 is fine.)

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Problem 8: 12 2/3 + 16 2/3

Whole numbers: 12 + 16 = 28

Fractions: 2/3 + 2/3 = 4/3 = 1 1/3

Total: 28 + 1 = 29, plus 1/3 → 29 1/3

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Problem 9: 1 3/7 + 11 2/8

Simplify 2/8 = 1/4

So: 1 3/7 + 11 1/4

Whole numbers: 1 + 11 = 12

Fractions: 3/7 + 1/4
Common denominator: 28
3/7 = 12/28
1/4 = 7/28
Add: 12/28 + 7/28 = 19/28

→ 12 19/28

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Problem 10: 14 6/9 + 17 3/7

Simplify 6/9 = 2/3

So: 14 2/3 + 17 3/7

Whole numbers: 14 + 17 = 31

Fractions: 2/3 + 3/7
Common denominator: 21
2/3 = 14/21
3/7 = 9/21
Add: 14/21 + 9/21 = 23/21 = 1 2/21

Total: 31 + 1 = 32, plus 2/21 → 32 2/21

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Final Answer:
1. 11 14/55
2. 11 1/12
3. 31 1/12
4. 31 29/66
5. 34 19/24
6. 26 13/21
7. 12
8. 29 1/3
9. 12 19/28
10. 32 2/21