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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 156 · 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. 1.450 + 78 =
  2. 2.242 + 67 =
  3. 3.438 + 19 =
  4. 4.64 + 38 =
  5. 5.274 + 19 =
  6. 6.260 + 39 =
  7. 7.266 + 18 =
  8. 8.322 + 57 =
  9. 9.62 + 78 =
  10. 10.175 + 89 =
  11. 11.287 + 89 =
  12. 12.433 + 17 =
  13. 13.481 + 39 =
  14. 14.54 + 39 =
  15. 15.337 + 98 =
  16. 16.104 + 48 =
  17. 17.246 + 99 =
  18. 18.164 + 87 =
  19. 19.291 + 49 =
  20. 20.336 + 77 =
  21. 21.212 + 79 =
  22. 22.478 + 99 =
  23. 23.143 + 77 =
  24. 24.408 + 27 =
  25. 25.467 + 38 =
  26. 26.388 + 47 =
  27. 27.489 + 17 =
  28. 28.77 + 79 =
  29. 29.236 + 97 =
  30. 30.29 + 39 =
  31. 31.99 + 99 =
  32. 32.71 + 78 =
  33. 33.126 + 49 =
  34. 34.246 + 99 =
  35. 35.422 + 87 =
  36. 36.363 + 99 =
  37. 37.221 + 99 =
  38. 38.40 + 29 =
  39. 39.48 + 59 =
  40. 40.113 + 77 =

Answer key

  1. 528
  2. 309
  3. 457
  4. 102
  5. 293
  6. 299
  7. 284
  8. 379
  9. 140
  10. 264
  11. 376
  12. 450
  13. 520
  14. 93
  15. 435
  16. 152
  17. 345
  18. 251
  19. 340
  20. 413
  21. 291
  22. 577
  23. 220
  24. 435
  25. 505
  26. 435
  27. 506
  28. 156
  29. 333
  30. 68
  31. 198
  32. 149
  33. 175
  34. 345
  35. 509
  36. 462
  37. 320
  38. 69
  39. 107
  40. 190

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