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 + 8 = 9 + 1 + (answer space) = (answer space)
Answer: 7, 17
- 9 + 1 = 10 (a ten)
- 10 + 7 = 17
2.7 + 7 = 7 + 3 + (answer space) = (answer space)
Answer: 4, 14
- 7 + 3 = 10 (a ten)
- 10 + 4 = 14
3.10 + 9 = (answer space) + (answer space) + 1 = (answer space)
Answer: 9, 9, 19
- Double 9 is 18
- 18 + 1 = 19
4.6 + 9 = 6 + 4 + (answer space) = (answer space)
Answer: 5, 15
- 6 + 4 = 10 (a ten)
- 10 + 5 = 15
5.8 + 8 = 8 + 2 + (answer space) = (answer space)
Answer: 6, 16
- 8 + 2 = 10 (a ten)
- 10 + 6 = 16
6.8 + 7 = (answer space) + (answer space) + 1 = (answer space)
Answer: 7, 7, 15
- Double 7 is 14
- 14 + 1 = 15
7.8 + 3 = 8 + 2 + (answer space) = (answer space)
Answer: 1, 11
- 8 + 2 = 10 (a ten)
- 10 + 1 = 11
8.6 + 5 = 6 + 4 + (answer space) = (answer space)
Answer: 1, 11
- 6 + 4 = 10 (a ten)
- 10 + 1 = 11
9.8 + 9 = (answer space) + (answer space) + 1 = (answer space)
Answer: 8, 8, 17
- Double 8 is 16
- 16 + 1 = 17
10.8 + 5 = 8 + 2 + (answer space) = (answer space)
Answer: 3, 13
- 8 + 2 = 10 (a ten)
- 10 + 3 = 13
11.8 + 9 = 8 + 2 + (answer space) = (answer space)
Answer: 7, 17
- 8 + 2 = 10 (a ten)
- 10 + 7 = 17
12.3 + 4 = (answer space) + (answer space) + 1 = (answer space)
Answer: 3, 3, 7
- Double 3 is 6
- 6 + 1 = 7
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.