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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 398 · 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. 1.452 + 58 =
  2. 2.229 + 48 =
  3. 3.163 + 49 =
  4. 4.291 + 38 =
  5. 5.231 + 77 =
  6. 6.284 + 38 =
  7. 7.94 + 79 =
  8. 8.123 + 18 =
  9. 9.37 + 47 =
  10. 10.415 + 49 =
  11. 11.476 + 78 =
  12. 12.308 + 37 =
  13. 13.495 + 78 =
  14. 14.158 + 37 =
  15. 15.498 + 29 =
  16. 16.121 + 79 =
  17. 17.119 + 28 =
  18. 18.448 + 39 =
  19. 19.237 + 18 =
  20. 20.390 + 38 =
  21. 21.345 + 78 =
  22. 22.266 + 39 =
  23. 23.377 + 48 =
  24. 24.47 + 38 =
  25. 25.26 + 18 =
  26. 26.27 + 68 =
  27. 27.354 + 67 =
  28. 28.286 + 57 =
  29. 29.461 + 67 =
  30. 30.223 + 77 =
  31. 31.170 + 29 =
  32. 32.327 + 97 =
  33. 33.62 + 99 =
  34. 34.457 + 68 =
  35. 35.101 + 79 =
  36. 36.433 + 97 =
  37. 37.474 + 39 =
  38. 38.372 + 87 =
  39. 39.342 + 99 =
  40. 40.34 + 17 =

Answer key

  1. 510
  2. 277
  3. 212
  4. 329
  5. 308
  6. 322
  7. 173
  8. 141
  9. 84
  10. 464
  11. 554
  12. 345
  13. 573
  14. 195
  15. 527
  16. 200
  17. 147
  18. 487
  19. 255
  20. 428
  21. 423
  22. 305
  23. 425
  24. 85
  25. 44
  26. 95
  27. 421
  28. 343
  29. 528
  30. 300
  31. 199
  32. 424
  33. 161
  34. 525
  35. 180
  36. 530
  37. 513
  38. 459
  39. 441
  40. 51

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