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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 380 · 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. 1.49 + 58 =
  2. 2.100 + 29 =
  3. 3.160 + 17 =
  4. 4.122 + 87 =
  5. 5.224 + 87 =
  6. 6.168 + 97 =
  7. 7.348 + 78 =
  8. 8.427 + 89 =
  9. 9.442 + 98 =
  10. 10.42 + 37 =
  11. 11.410 + 19 =
  12. 12.434 + 98 =
  13. 13.81 + 87 =
  14. 14.208 + 39 =
  15. 15.156 + 48 =
  16. 16.89 + 87 =
  17. 17.81 + 27 =
  18. 18.329 + 69 =
  19. 19.278 + 49 =
  20. 20.472 + 77 =
  21. 21.475 + 97 =
  22. 22.117 + 18 =
  23. 23.34 + 29 =
  24. 24.185 + 27 =
  25. 25.446 + 89 =
  26. 26.311 + 28 =
  27. 27.26 + 87 =
  28. 28.195 + 97 =
  29. 29.304 + 39 =
  30. 30.264 + 98 =
  31. 31.396 + 49 =
  32. 32.368 + 39 =
  33. 33.323 + 29 =
  34. 34.43 + 98 =
  35. 35.115 + 28 =
  36. 36.288 + 18 =
  37. 37.436 + 28 =
  38. 38.474 + 28 =
  39. 39.160 + 89 =
  40. 40.56 + 79 =

Answer key

  1. 107
  2. 129
  3. 177
  4. 209
  5. 311
  6. 265
  7. 426
  8. 516
  9. 540
  10. 79
  11. 429
  12. 532
  13. 168
  14. 247
  15. 204
  16. 176
  17. 108
  18. 398
  19. 327
  20. 549
  21. 572
  22. 135
  23. 63
  24. 212
  25. 535
  26. 339
  27. 113
  28. 292
  29. 343
  30. 362
  31. 445
  32. 407
  33. 352
  34. 141
  35. 143
  36. 306
  37. 464
  38. 502
  39. 249
  40. 135

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