Year 3 Mental Addition and Subtraction Strategies Worksheet — Level 1 — 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 — Answers
Fill in each step of the strategy, then write the answer.
1.8 + 5 = 8 + 2 + (answer space) = (answer space)
Answer: 3, 13
- 8 + 2 = 10 (a ten)
- 10 + 3 = 13
2.6 + 7 = 6 + 4 + (answer space) = (answer space)
Answer: 3, 13
- 6 + 4 = 10 (a ten)
- 10 + 3 = 13
3.7 + 6 = (answer space) + (answer space) + 1 = (answer space)
Answer: 6, 6, 13
- Double 6 is 12
- 12 + 1 = 13
4.8 + 6 = 8 + 2 + (answer space) = (answer space)
Answer: 4, 14
- 8 + 2 = 10 (a ten)
- 10 + 4 = 14
5.7 + 8 = 7 + 3 + (answer space) = (answer space)
Answer: 5, 15
- 7 + 3 = 10 (a ten)
- 10 + 5 = 15
6.6 + 5 = (answer space) + (answer space) + 1 = (answer space)
Answer: 5, 5, 11
- Double 5 is 10
- 10 + 1 = 11
7.6 + 5 = 6 + 4 + (answer space) = (answer space)
Answer: 1, 11
- 6 + 4 = 10 (a ten)
- 10 + 1 = 11
8.9 + 7 = 9 + 1 + (answer space) = (answer space)
Answer: 6, 16
- 9 + 1 = 10 (a ten)
- 10 + 6 = 16
9.8 + 9 = (answer space) + (answer space) + 1 = (answer space)
Answer: 8, 8, 17
- Double 8 is 16
- 16 + 1 = 17
10.6 + 9 = 6 + 4 + (answer space) = (answer space)
Answer: 5, 15
- 6 + 4 = 10 (a ten)
- 10 + 5 = 15
11.9 + 9 = 9 + 1 + (answer space) = (answer space)
Answer: 8, 18
- 9 + 1 = 10 (a ten)
- 10 + 8 = 18
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.