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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 364 · 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. 1.137 + 39 =
  2. 2.214 + 19 =
  3. 3.61 + 67 =
  4. 4.423 + 88 =
  5. 5.323 + 97 =
  6. 6.293 + 17 =
  7. 7.56 + 39 =
  8. 8.155 + 39 =
  9. 9.480 + 67 =
  10. 10.211 + 18 =
  11. 11.86 + 67 =
  12. 12.495 + 58 =
  13. 13.310 + 49 =
  14. 14.359 + 27 =
  15. 15.211 + 57 =
  16. 16.150 + 47 =
  17. 17.439 + 19 =
  18. 18.46 + 89 =
  19. 19.329 + 17 =
  20. 20.221 + 59 =
  21. 21.472 + 27 =
  22. 22.260 + 77 =
  23. 23.286 + 19 =
  24. 24.189 + 88 =
  25. 25.335 + 47 =
  26. 26.420 + 47 =
  27. 27.298 + 69 =
  28. 28.255 + 28 =
  29. 29.63 + 67 =
  30. 30.285 + 67 =
  31. 31.38 + 38 =
  32. 32.154 + 79 =
  33. 33.315 + 89 =
  34. 34.97 + 39 =
  35. 35.325 + 39 =
  36. 36.61 + 18 =
  37. 37.198 + 78 =
  38. 38.180 + 19 =
  39. 39.87 + 28 =
  40. 40.463 + 47 =

Answer key

  1. 176
  2. 233
  3. 128
  4. 511
  5. 420
  6. 310
  7. 95
  8. 194
  9. 547
  10. 229
  11. 153
  12. 553
  13. 359
  14. 386
  15. 268
  16. 197
  17. 458
  18. 135
  19. 346
  20. 280
  21. 499
  22. 337
  23. 305
  24. 277
  25. 382
  26. 467
  27. 367
  28. 283
  29. 130
  30. 352
  31. 76
  32. 233
  33. 404
  34. 136
  35. 364
  36. 79
  37. 276
  38. 199
  39. 115
  40. 510

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