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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 124 · 40 questions
TalentJR

The fast method (Round up, then fix): Round the number ending in 7, 8 or 9 up to the next ten: 39 → 40. Add the round number. Take away the extra you added (here 1).

NameDateTime takenScore ___ / 40
  1. 1.317 + 28 =
  2. 2.486 + 19 =
  3. 3.324 + 89 =
  4. 4.481 + 49 =
  5. 5.212 + 17 =
  6. 6.66 + 67 =
  7. 7.304 + 67 =
  8. 8.338 + 69 =
  9. 9.424 + 29 =
  10. 10.118 + 29 =
  11. 11.138 + 79 =
  12. 12.156 + 37 =
  13. 13.199 + 77 =
  14. 14.85 + 99 =
  15. 15.405 + 89 =
  16. 16.49 + 37 =
  17. 17.113 + 57 =
  18. 18.331 + 77 =
  19. 19.273 + 78 =
  20. 20.426 + 39 =
  21. 21.118 + 19 =
  22. 22.157 + 58 =
  23. 23.258 + 79 =
  24. 24.60 + 17 =
  25. 25.125 + 67 =
  26. 26.417 + 29 =
  27. 27.496 + 79 =
  28. 28.308 + 87 =
  29. 29.159 + 27 =
  30. 30.302 + 49 =
  31. 31.472 + 58 =
  32. 32.303 + 59 =
  33. 33.109 + 59 =
  34. 34.379 + 39 =
  35. 35.486 + 28 =
  36. 36.462 + 97 =
  37. 37.305 + 29 =
  38. 38.480 + 28 =
  39. 39.494 + 68 =
  40. 40.74 + 99 =

Answer key

  1. 345
  2. 505
  3. 413
  4. 530
  5. 229
  6. 133
  7. 371
  8. 407
  9. 453
  10. 147
  11. 217
  12. 193
  13. 276
  14. 184
  15. 494
  16. 86
  17. 170
  18. 408
  19. 351
  20. 465
  21. 137
  22. 215
  23. 337
  24. 77
  25. 192
  26. 446
  27. 575
  28. 395
  29. 186
  30. 351
  31. 530
  32. 362
  33. 168
  34. 418
  35. 514
  36. 559
  37. 334
  38. 508
  39. 562
  40. 173

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