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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 485 · 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. 1.391 + 98 =
  2. 2.450 + 97 =
  3. 3.30 + 37 =
  4. 4.48 + 57 =
  5. 5.423 + 89 =
  6. 6.264 + 79 =
  7. 7.176 + 59 =
  8. 8.434 + 47 =
  9. 9.287 + 48 =
  10. 10.298 + 27 =
  11. 11.387 + 47 =
  12. 12.320 + 27 =
  13. 13.189 + 17 =
  14. 14.71 + 18 =
  15. 15.157 + 69 =
  16. 16.424 + 47 =
  17. 17.324 + 48 =
  18. 18.328 + 77 =
  19. 19.416 + 27 =
  20. 20.41 + 37 =
  21. 21.409 + 79 =
  22. 22.91 + 37 =
  23. 23.99 + 38 =
  24. 24.189 + 58 =
  25. 25.209 + 17 =
  26. 26.183 + 39 =
  27. 27.369 + 47 =
  28. 28.298 + 97 =
  29. 29.236 + 87 =
  30. 30.290 + 18 =
  31. 31.357 + 17 =
  32. 32.191 + 78 =
  33. 33.76 + 59 =
  34. 34.489 + 89 =
  35. 35.274 + 88 =
  36. 36.468 + 87 =
  37. 37.469 + 49 =
  38. 38.259 + 58 =
  39. 39.163 + 88 =
  40. 40.491 + 17 =

Answer key

  1. 489
  2. 547
  3. 67
  4. 105
  5. 512
  6. 343
  7. 235
  8. 481
  9. 335
  10. 325
  11. 434
  12. 347
  13. 206
  14. 89
  15. 226
  16. 471
  17. 372
  18. 405
  19. 443
  20. 78
  21. 488
  22. 128
  23. 137
  24. 247
  25. 226
  26. 222
  27. 416
  28. 395
  29. 323
  30. 308
  31. 374
  32. 269
  33. 135
  34. 578
  35. 362
  36. 555
  37. 518
  38. 317
  39. 251
  40. 508

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