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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 570 · 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. 1.381 + 29 =
  2. 2.163 + 98 =
  3. 3.110 + 49 =
  4. 4.126 + 77 =
  5. 5.91 + 79 =
  6. 6.404 + 79 =
  7. 7.59 + 79 =
  8. 8.409 + 67 =
  9. 9.242 + 89 =
  10. 10.493 + 17 =
  11. 11.287 + 69 =
  12. 12.399 + 27 =
  13. 13.443 + 29 =
  14. 14.82 + 18 =
  15. 15.155 + 99 =
  16. 16.352 + 89 =
  17. 17.417 + 99 =
  18. 18.407 + 17 =
  19. 19.73 + 19 =
  20. 20.471 + 48 =
  21. 21.347 + 18 =
  22. 22.427 + 58 =
  23. 23.54 + 98 =
  24. 24.176 + 58 =
  25. 25.175 + 59 =
  26. 26.116 + 58 =
  27. 27.455 + 27 =
  28. 28.397 + 27 =
  29. 29.372 + 17 =
  30. 30.425 + 27 =
  31. 31.409 + 77 =
  32. 32.146 + 97 =
  33. 33.305 + 48 =
  34. 34.37 + 17 =
  35. 35.202 + 78 =
  36. 36.207 + 19 =
  37. 37.322 + 57 =
  38. 38.105 + 99 =
  39. 39.83 + 97 =
  40. 40.450 + 39 =

Answer key

  1. 410
  2. 261
  3. 159
  4. 203
  5. 170
  6. 483
  7. 138
  8. 476
  9. 331
  10. 510
  11. 356
  12. 426
  13. 472
  14. 100
  15. 254
  16. 441
  17. 516
  18. 424
  19. 92
  20. 519
  21. 365
  22. 485
  23. 152
  24. 234
  25. 234
  26. 174
  27. 482
  28. 424
  29. 389
  30. 452
  31. 486
  32. 243
  33. 353
  34. 54
  35. 280
  36. 226
  37. 379
  38. 204
  39. 180
  40. 489

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