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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 392 · 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. 1.499 − 267 =
  2. 2.506 + 318 =
  3. 3.904 − 121 =
  4. 4.451 − 205 =
  5. 5.513 − 368 =
  6. 6.947 − 126 =
  7. 7.739 + 291 =
  8. 8.477 + 599 =
  9. 9.175 + 316 =
  10. 10.182 + 233 =
  11. 11.981 − 667 =
  12. 12.322 + 175 =
  13. 13.298 + 495 =
  14. 14.492 − 225 =
  15. 15.466 − 349 =
  16. 16.201 + 457 =
  17. 17.672 − 292 =
  18. 18.414 − 231 =
  19. 19.193 + 549 =
  20. 20.772 + 249 =
  21. 21.963 − 451 =
  22. 22.132 + 304 =
  23. 23.731 − 141 =
  24. 24.228 + 611 =
  25. 25.226 + 315 =
  26. 26.249 + 606 =
  27. 27.681 − 132 =
  28. 28.543 + 142 =
  29. 29.391 + 529 =
  30. 30.786 − 222 =
  31. 31.309 + 589 =
  32. 32.652 + 439 =
  33. 33.699 − 215 =
  34. 34.618 + 256 =
  35. 35.827 − 711 =
  36. 36.901 − 486 =
  37. 37.882 − 331 =
  38. 38.602 − 426 =
  39. 39.634 + 567 =
  40. 40.787 − 357 =

Answer key

  1. 232
  2. 824
  3. 783
  4. 246
  5. 145
  6. 821
  7. 1030
  8. 1076
  9. 491
  10. 415
  11. 314
  12. 497
  13. 793
  14. 267
  15. 117
  16. 658
  17. 380
  18. 183
  19. 742
  20. 1021
  21. 512
  22. 436
  23. 590
  24. 839
  25. 541
  26. 855
  27. 549
  28. 685
  29. 920
  30. 564
  31. 898
  32. 1091
  33. 484
  34. 874
  35. 116
  36. 415
  37. 551
  38. 176
  39. 1201
  40. 430

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