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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 9 · 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. 1.309 + 578 =
  2. 2.318 + 252 =
  3. 3.711 + 138 =
  4. 4.296 + 442 =
  5. 5.729 − 292 =
  6. 6.617 + 476 =
  7. 7.255 + 556 =
  8. 8.242 + 502 =
  9. 9.198 + 138 =
  10. 10.311 + 441 =
  11. 11.519 − 243 =
  12. 12.762 − 583 =
  13. 13.696 − 168 =
  14. 14.579 − 232 =
  15. 15.252 + 159 =
  16. 16.974 − 701 =
  17. 17.879 − 138 =
  18. 18.691 + 151 =
  19. 19.440 − 205 =
  20. 20.291 + 594 =
  21. 21.508 − 271 =
  22. 22.776 − 274 =
  23. 23.609 + 441 =
  24. 24.780 + 189 =
  25. 25.427 − 179 =
  26. 26.720 − 394 =
  27. 27.761 − 314 =
  28. 28.465 + 321 =
  29. 29.450 + 181 =
  30. 30.969 − 127 =
  31. 31.448 − 134 =
  32. 32.453 − 286 =
  33. 33.578 − 181 =
  34. 34.435 − 183 =
  35. 35.291 + 689 =
  36. 36.717 + 607 =
  37. 37.235 + 146 =
  38. 38.260 + 547 =
  39. 39.648 + 311 =
  40. 40.881 − 498 =

Answer key

  1. 887
  2. 570
  3. 849
  4. 738
  5. 437
  6. 1093
  7. 811
  8. 744
  9. 336
  10. 752
  11. 276
  12. 179
  13. 528
  14. 347
  15. 411
  16. 273
  17. 741
  18. 842
  19. 235
  20. 885
  21. 237
  22. 502
  23. 1050
  24. 969
  25. 248
  26. 326
  27. 447
  28. 786
  29. 631
  30. 842
  31. 314
  32. 167
  33. 397
  34. 252
  35. 980
  36. 1324
  37. 381
  38. 807
  39. 959
  40. 383

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