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Add by Rounding Worksheet

Speed calculation lesson 2: Add by rounding · Set 512 · 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. 1.172 + 27 =
  2. 2.466 + 88 =
  3. 3.223 + 98 =
  4. 4.259 + 48 =
  5. 5.404 + 29 =
  6. 6.477 + 58 =
  7. 7.385 + 67 =
  8. 8.80 + 47 =
  9. 9.402 + 98 =
  10. 10.86 + 97 =
  11. 11.279 + 99 =
  12. 12.58 + 77 =
  13. 13.58 + 47 =
  14. 14.300 + 68 =
  15. 15.228 + 59 =
  16. 16.443 + 27 =
  17. 17.44 + 78 =
  18. 18.323 + 49 =
  19. 19.90 + 78 =
  20. 20.33 + 18 =
  21. 21.475 + 97 =
  22. 22.452 + 18 =
  23. 23.457 + 99 =
  24. 24.261 + 78 =
  25. 25.482 + 39 =
  26. 26.67 + 39 =
  27. 27.131 + 69 =
  28. 28.323 + 28 =
  29. 29.412 + 38 =
  30. 30.37 + 29 =
  31. 31.280 + 38 =
  32. 32.398 + 28 =
  33. 33.421 + 79 =
  34. 34.342 + 58 =
  35. 35.467 + 28 =
  36. 36.274 + 69 =
  37. 37.255 + 67 =
  38. 38.392 + 89 =
  39. 39.161 + 28 =
  40. 40.464 + 38 =

Answer key

  1. 199
  2. 554
  3. 321
  4. 307
  5. 433
  6. 535
  7. 452
  8. 127
  9. 500
  10. 183
  11. 378
  12. 135
  13. 105
  14. 368
  15. 287
  16. 470
  17. 122
  18. 372
  19. 168
  20. 51
  21. 572
  22. 470
  23. 556
  24. 339
  25. 521
  26. 106
  27. 200
  28. 351
  29. 450
  30. 66
  31. 318
  32. 426
  33. 500
  34. 400
  35. 495
  36. 343
  37. 322
  38. 481
  39. 189
  40. 502

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