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Year 3 Mental Addition and Subtraction Strategies Worksheet — Level 3 — Practice Set 2 — Answers

Answer sheet with worked solutions for the Year 3 addition worksheet.

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Success TutoringWorksheetsAnswer sheetYear 3 · Mathematics · Addition

Year 3 Mental Addition and Subtraction Strategies Worksheet — Level 3 — Practice Set 2 — Answers

Fill in each step of the strategy, then write the answer.

1.78 + 29 = 78 + 30 − (answer space) = (answer space)

Answer: 1, 107

  1. 78 + 30 = 108
  2. 108 − 1 = 107
2.50 − 18 = 50 − 20 + (answer space) = (answer space)

Answer: 2, 32

  1. 50 − 20 = 30
  2. I took away 2 too many, so add it back: 30 + 2 = 32
3.171 − 7 = 171 − 1 − (answer space) = (answer space)

Answer: 6, 164

  1. 171 − 1 = 170 (back to a ten)
  2. 170 − 6 = 164
4.163 + 49 = 163 + 50 − (answer space) = (answer space)

Answer: 1, 212

  1. 163 + 50 = 213
  2. 213 − 1 = 212
5.218 − 98 = 218 − 100 + (answer space) = (answer space)

Answer: 2, 120

  1. 218 − 100 = 118
  2. I took away 2 too many, so add it back: 118 + 2 = 120
6.141 − 9 = 141 − 1 − (answer space) = (answer space)

Answer: 8, 132

  1. 141 − 1 = 140 (back to a ten)
  2. 140 − 8 = 132
7.28 + 28 = 28 + 30 − (answer space) = (answer space)

Answer: 2, 56

  1. 28 + 30 = 58
  2. 58 − 2 = 56
8.120 − 9 = 120 − 10 + (answer space) = (answer space)

Answer: 1, 111

  1. 120 − 10 = 110
  2. I took away 1 too many, so add it back: 110 + 1 = 111
9.71 − 6 = 71 − 1 − (answer space) = (answer space)

Answer: 5, 65

  1. 71 − 1 = 70 (back to a ten)
  2. 70 − 5 = 65
10.150 + 49 = 150 + 50 − (answer space) = (answer space)

Answer: 1, 199

  1. 150 + 50 = 200
  2. 200 − 1 = 199
11.114 − 9 = 114 − 10 + (answer space) = (answer space)

Answer: 1, 105

  1. 114 − 10 = 104
  2. I took away 1 too many, so add it back: 104 + 1 = 105
12.83 − 7 = 83 − 3 − (answer space) = (answer space)

Answer: 4, 76

  1. 83 − 3 = 80 (back to a ten)
  2. 80 − 4 = 76
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