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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 123 · 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. 1.281 + 39 =
  2. 2.268 + 28 =
  3. 3.399 + 88 =
  4. 4.439 + 29 =
  5. 5.169 + 59 =
  6. 6.73 + 89 =
  7. 7.221 + 78 =
  8. 8.390 + 97 =
  9. 9.52 + 29 =
  10. 10.81 + 49 =
  11. 11.52 + 38 =
  12. 12.193 + 48 =
  13. 13.55 + 18 =
  14. 14.224 + 49 =
  15. 15.75 + 28 =
  16. 16.481 + 97 =
  17. 17.139 + 17 =
  18. 18.317 + 38 =
  19. 19.183 + 69 =
  20. 20.229 + 18 =
  21. 21.63 + 57 =
  22. 22.404 + 58 =
  23. 23.332 + 58 =
  24. 24.115 + 67 =
  25. 25.264 + 67 =
  26. 26.214 + 79 =
  27. 27.393 + 49 =
  28. 28.476 + 47 =
  29. 29.62 + 59 =
  30. 30.328 + 19 =
  31. 31.62 + 48 =
  32. 32.353 + 28 =
  33. 33.224 + 48 =
  34. 34.412 + 28 =
  35. 35.423 + 88 =
  36. 36.319 + 68 =
  37. 37.107 + 37 =
  38. 38.348 + 17 =
  39. 39.28 + 18 =
  40. 40.37 + 17 =

Answer key

  1. 320
  2. 296
  3. 487
  4. 468
  5. 228
  6. 162
  7. 299
  8. 487
  9. 81
  10. 130
  11. 90
  12. 241
  13. 73
  14. 273
  15. 103
  16. 578
  17. 156
  18. 355
  19. 252
  20. 247
  21. 120
  22. 462
  23. 390
  24. 182
  25. 331
  26. 293
  27. 442
  28. 523
  29. 121
  30. 347
  31. 110
  32. 381
  33. 272
  34. 440
  35. 511
  36. 387
  37. 144
  38. 365
  39. 46
  40. 54

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