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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 183 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.294 + 387 =
  2. 2.767 + 263 =
  3. 3.620 + 237 =
  4. 4.692 − 287 =
  5. 5.252 + 441 =
  6. 6.421 − 181 =
  7. 7.713 − 571 =
  8. 8.763 + 172 =
  9. 9.479 − 373 =
  10. 10.576 + 366 =
  11. 11.710 − 348 =
  12. 12.702 − 571 =
  13. 13.823 − 555 =
  14. 14.148 + 537 =
  15. 15.948 − 589 =
  16. 16.545 − 385 =
  17. 17.216 + 512 =
  18. 18.170 + 551 =
  19. 19.560 − 195 =
  20. 20.453 − 218 =
  21. 21.605 − 162 =
  22. 22.589 − 321 =
  23. 23.731 + 362 =
  24. 24.599 − 324 =
  25. 25.512 + 251 =
  26. 26.224 + 173 =
  27. 27.626 + 234 =
  28. 28.703 + 296 =
  29. 29.348 + 673 =
  30. 30.512 − 245 =
  31. 31.580 + 593 =
  32. 32.516 − 394 =
  33. 33.471 + 573 =
  34. 34.786 − 684 =
  35. 35.510 + 306 =
  36. 36.664 − 175 =
  37. 37.466 − 289 =
  38. 38.987 − 364 =
  39. 39.455 − 245 =
  40. 40.171 + 605 =

Answer key

  1. 681
  2. 1030
  3. 857
  4. 405
  5. 693
  6. 240
  7. 142
  8. 935
  9. 106
  10. 942
  11. 362
  12. 131
  13. 268
  14. 685
  15. 359
  16. 160
  17. 728
  18. 721
  19. 365
  20. 235
  21. 443
  22. 268
  23. 1093
  24. 275
  25. 763
  26. 397
  27. 860
  28. 999
  29. 1021
  30. 267
  31. 1173
  32. 122
  33. 1044
  34. 102
  35. 816
  36. 489
  37. 177
  38. 623
  39. 210
  40. 776

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