3rd Grade Mental Addition and Subtraction Strategies Worksheet — Level 2 — Answers
Answer sheet with worked solutions for the 3rd Grade addition worksheet.
Success TutoringWorksheetsAnswer sheet3rd Grade · Mathematics · Addition3rd Grade Mental Addition and Subtraction Strategies Worksheet — Level 2 — Answers
Fill in each step of the strategy, then write the answer.
1.79 + 7 = 79 + 1 + (answer space) = (answer space)
Answer: 6, 86
- 79 + 1 = 80 (a ten)
- 80 + 6 = 86
2.23 + 9 = 23 + 10 − (answer space) = (answer space)
Answer: 1, 32
- 23 + 10 = 33
- 33 − 1 = 32
3.11 + 12 = (answer space) + (answer space) + 1 = (answer space)
Answer: 11, 11, 23
- Double 11 is 22
- 22 + 1 = 23
4.25 + 7 = 25 + 5 + (answer space) = (answer space)
Answer: 2, 32
- 25 + 5 = 30 (a ten)
- 30 + 2 = 32
5.67 + 9 = 67 + 10 − (answer space) = (answer space)
Answer: 1, 76
- 67 + 10 = 77
- 77 − 1 = 76
6.51 + 52 = (answer space) + (answer space) + 1 = (answer space)
Answer: 51, 51, 103
- Double 51 is 102
- 102 + 1 = 103
7.56 + 8 = 56 + 4 + (answer space) = (answer space)
Answer: 4, 64
- 56 + 4 = 60 (a ten)
- 60 + 4 = 64
8.12 + 9 = 12 + 10 − (answer space) = (answer space)
Answer: 1, 21
- 12 + 10 = 22
- 22 − 1 = 21
9.31 + 32 = (answer space) + (answer space) + 1 = (answer space)
Answer: 31, 31, 63
- Double 31 is 62
- 62 + 1 = 63
10.45 + 9 = 45 + 5 + (answer space) = (answer space)
Answer: 4, 54
- 45 + 5 = 50 (a ten)
- 50 + 4 = 54
11.79 + 9 = 79 + 10 − (answer space) = (answer space)
Answer: 1, 88
- 79 + 10 = 89
- 89 − 1 = 88
12.61 + 62 = (answer space) + (answer space) + 1 = (answer space)
Answer: 61, 61, 123
- Double 61 is 122
- 122 + 1 = 123
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.