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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 810 · 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. 1.123 + 38 =
  2. 2.83 + 77 =
  3. 3.265 + 59 =
  4. 4.270 + 57 =
  5. 5.253 + 28 =
  6. 6.107 + 37 =
  7. 7.163 + 49 =
  8. 8.463 + 89 =
  9. 9.380 + 28 =
  10. 10.80 + 79 =
  11. 11.128 + 18 =
  12. 12.145 + 89 =
  13. 13.372 + 28 =
  14. 14.336 + 77 =
  15. 15.92 + 88 =
  16. 16.400 + 38 =
  17. 17.52 + 27 =
  18. 18.359 + 79 =
  19. 19.326 + 38 =
  20. 20.480 + 67 =
  21. 21.147 + 17 =
  22. 22.481 + 37 =
  23. 23.447 + 99 =
  24. 24.445 + 18 =
  25. 25.52 + 99 =
  26. 26.469 + 79 =
  27. 27.335 + 18 =
  28. 28.149 + 67 =
  29. 29.464 + 89 =
  30. 30.177 + 69 =
  31. 31.133 + 89 =
  32. 32.284 + 27 =
  33. 33.428 + 88 =
  34. 34.162 + 67 =
  35. 35.407 + 39 =
  36. 36.119 + 87 =
  37. 37.97 + 79 =
  38. 38.446 + 87 =
  39. 39.459 + 99 =
  40. 40.354 + 57 =

Answer key

  1. 161
  2. 160
  3. 324
  4. 327
  5. 281
  6. 144
  7. 212
  8. 552
  9. 408
  10. 159
  11. 146
  12. 234
  13. 400
  14. 413
  15. 180
  16. 438
  17. 79
  18. 438
  19. 364
  20. 547
  21. 164
  22. 518
  23. 546
  24. 463
  25. 151
  26. 548
  27. 353
  28. 216
  29. 553
  30. 246
  31. 222
  32. 311
  33. 516
  34. 229
  35. 446
  36. 206
  37. 176
  38. 533
  39. 558
  40. 411

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