Year 3 Mental Addition and Subtraction Strategies Worksheet — Level 1 — Practice Set 3 — Answers
Answer sheet with worked solutions for the Year 3 addition worksheet.
Success TutoringWorksheetsAnswer sheetYear 3 · Mathematics · AdditionYear 3 Mental Addition and Subtraction Strategies Worksheet — Level 1 — Practice Set 3 — Answers
Fill in each step of the strategy, then write the answer.
1.9 + 3 = 9 + 1 + (answer space) = (answer space)
Answer: 2, 12
- 9 + 1 = 10 (a ten)
- 10 + 2 = 12
2.9 + 8 = 9 + 1 + (answer space) = (answer space)
Answer: 7, 17
- 9 + 1 = 10 (a ten)
- 10 + 7 = 17
3.6 + 7 = (answer space) + (answer space) + 1 = (answer space)
Answer: 6, 6, 13
- Double 6 is 12
- 12 + 1 = 13
4.9 + 9 = 9 + 1 + (answer space) = (answer space)
Answer: 8, 18
- 9 + 1 = 10 (a ten)
- 10 + 8 = 18
5.7 + 5 = 7 + 3 + (answer space) = (answer space)
Answer: 2, 12
- 7 + 3 = 10 (a ten)
- 10 + 2 = 12
6.7 + 6 = (answer space) + (answer space) + 1 = (answer space)
Answer: 6, 6, 13
- Double 6 is 12
- 12 + 1 = 13
7.7 + 6 = 7 + 3 + (answer space) = (answer space)
Answer: 3, 13
- 7 + 3 = 10 (a ten)
- 10 + 3 = 13
8.9 + 2 = 9 + 1 + (answer space) = (answer space)
Answer: 1, 11
- 9 + 1 = 10 (a ten)
- 10 + 1 = 11
9.10 + 9 = (answer space) + (answer space) + 1 = (answer space)
Answer: 9, 9, 19
- Double 9 is 18
- 18 + 1 = 19
10.7 + 9 = 7 + 3 + (answer space) = (answer space)
Answer: 6, 16
- 7 + 3 = 10 (a ten)
- 10 + 6 = 16
11.9 + 7 = 9 + 1 + (answer space) = (answer space)
Answer: 6, 16
- 9 + 1 = 10 (a ten)
- 10 + 6 = 16
12.8 + 7 = (answer space) + (answer space) + 1 = (answer space)
Answer: 7, 7, 15
- Double 7 is 14
- 14 + 1 = 15
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.