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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 382 · 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. 1.703 − 267 =
  2. 2.762 + 201 =
  3. 3.253 + 172 =
  4. 4.125 + 259 =
  5. 5.240 + 586 =
  6. 6.739 + 437 =
  7. 7.643 + 236 =
  8. 8.419 + 675 =
  9. 9.415 − 303 =
  10. 10.504 + 265 =
  11. 11.755 − 192 =
  12. 12.651 + 414 =
  13. 13.309 + 436 =
  14. 14.289 + 614 =
  15. 15.325 + 351 =
  16. 16.948 − 683 =
  17. 17.903 − 776 =
  18. 18.426 + 199 =
  19. 19.628 + 151 =
  20. 20.508 − 166 =
  21. 21.717 − 422 =
  22. 22.497 + 396 =
  23. 23.453 − 277 =
  24. 24.612 + 617 =
  25. 25.211 + 261 =
  26. 26.738 − 278 =
  27. 27.716 − 251 =
  28. 28.415 − 284 =
  29. 29.526 − 371 =
  30. 30.443 − 158 =
  31. 31.545 − 189 =
  32. 32.728 + 581 =
  33. 33.774 − 571 =
  34. 34.534 − 343 =
  35. 35.600 − 405 =
  36. 36.676 + 151 =
  37. 37.477 + 201 =
  38. 38.210 + 165 =
  39. 39.748 + 141 =
  40. 40.186 + 613 =

Answer key

  1. 436
  2. 963
  3. 425
  4. 384
  5. 826
  6. 1176
  7. 879
  8. 1094
  9. 112
  10. 769
  11. 563
  12. 1065
  13. 745
  14. 903
  15. 676
  16. 265
  17. 127
  18. 625
  19. 779
  20. 342
  21. 295
  22. 893
  23. 176
  24. 1229
  25. 472
  26. 460
  27. 465
  28. 131
  29. 155
  30. 285
  31. 356
  32. 1309
  33. 203
  34. 191
  35. 195
  36. 827
  37. 678
  38. 375
  39. 889
  40. 799

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