3rd Grade Mental Addition and Subtraction Strategies Worksheet — Level 2 — Practice Set 3 — 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 — Practice Set 3 — Answers
Fill in each step of the strategy, then write the answer.
1.19 + 3 = 19 + 1 + (answer space) = (answer space)
Answer: 2, 22
- 19 + 1 = 20 (a ten)
- 20 + 2 = 22
2.41 + 9 = 41 + 10 − (answer space) = (answer space)
Answer: 1, 50
- 41 + 10 = 51
- 51 − 1 = 50
3.15 + 14 = (answer space) + (answer space) + 1 = (answer space)
Answer: 14, 14, 29
- Double 14 is 28
- 28 + 1 = 29
4.16 + 9 = 16 + 4 + (answer space) = (answer space)
Answer: 5, 25
- 16 + 4 = 20 (a ten)
- 20 + 5 = 25
5.33 + 9 = 33 + 10 − (answer space) = (answer space)
Answer: 1, 42
- 33 + 10 = 43
- 43 − 1 = 42
6.80 + 81 = (answer space) + (answer space) + 1 = (answer space)
Answer: 80, 80, 161
- Double 80 is 160
- 160 + 1 = 161
7.25 + 9 = 25 + 5 + (answer space) = (answer space)
Answer: 4, 34
- 25 + 5 = 30 (a ten)
- 30 + 4 = 34
8.52 + 9 = 52 + 10 − (answer space) = (answer space)
Answer: 1, 61
- 52 + 10 = 62
- 62 − 1 = 61
9.22 + 21 = (answer space) + (answer space) + 1 = (answer space)
Answer: 21, 21, 43
- Double 21 is 42
- 42 + 1 = 43
10.87 + 5 = 87 + 3 + (answer space) = (answer space)
Answer: 2, 92
- 87 + 3 = 90 (a ten)
- 90 + 2 = 92
11.36 + 9 = 36 + 10 − (answer space) = (answer space)
Answer: 1, 45
- 36 + 10 = 46
- 46 − 1 = 45
12.18 + 17 = (answer space) + (answer space) + 1 = (answer space)
Answer: 17, 17, 35
- Double 17 is 34
- 34 + 1 = 35
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.