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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 390 · 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. 1.438 + 48 =
  2. 2.329 + 77 =
  3. 3.487 + 68 =
  4. 4.51 + 59 =
  5. 5.30 + 29 =
  6. 6.480 + 27 =
  7. 7.469 + 79 =
  8. 8.321 + 18 =
  9. 9.145 + 27 =
  10. 10.172 + 67 =
  11. 11.437 + 28 =
  12. 12.226 + 98 =
  13. 13.333 + 18 =
  14. 14.420 + 98 =
  15. 15.99 + 47 =
  16. 16.212 + 49 =
  17. 17.240 + 49 =
  18. 18.82 + 97 =
  19. 19.59 + 39 =
  20. 20.319 + 68 =
  21. 21.404 + 17 =
  22. 22.498 + 19 =
  23. 23.56 + 77 =
  24. 24.80 + 67 =
  25. 25.371 + 28 =
  26. 26.62 + 97 =
  27. 27.116 + 37 =
  28. 28.215 + 69 =
  29. 29.47 + 37 =
  30. 30.409 + 49 =
  31. 31.163 + 27 =
  32. 32.107 + 19 =
  33. 33.308 + 37 =
  34. 34.251 + 27 =
  35. 35.255 + 68 =
  36. 36.164 + 57 =
  37. 37.432 + 27 =
  38. 38.444 + 18 =
  39. 39.432 + 37 =
  40. 40.266 + 59 =

Answer key

  1. 486
  2. 406
  3. 555
  4. 110
  5. 59
  6. 507
  7. 548
  8. 339
  9. 172
  10. 239
  11. 465
  12. 324
  13. 351
  14. 518
  15. 146
  16. 261
  17. 289
  18. 179
  19. 98
  20. 387
  21. 421
  22. 517
  23. 133
  24. 147
  25. 399
  26. 159
  27. 153
  28. 284
  29. 84
  30. 458
  31. 190
  32. 126
  33. 345
  34. 278
  35. 323
  36. 221
  37. 459
  38. 462
  39. 469
  40. 325

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