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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 209 · 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. 1.798 − 617 =
  2. 2.488 − 321 =
  3. 3.390 + 589 =
  4. 4.911 − 189 =
  5. 5.864 − 589 =
  6. 6.304 + 498 =
  7. 7.518 − 341 =
  8. 8.284 + 138 =
  9. 9.225 + 667 =
  10. 10.623 − 258 =
  11. 11.866 − 156 =
  12. 12.664 + 131 =
  13. 13.436 + 547 =
  14. 14.693 + 364 =
  15. 15.396 + 502 =
  16. 16.949 − 332 =
  17. 17.298 + 416 =
  18. 18.371 + 661 =
  19. 19.775 + 325 =
  20. 20.799 − 488 =
  21. 21.454 + 528 =
  22. 22.452 + 676 =
  23. 23.467 − 115 =
  24. 24.606 + 258 =
  25. 25.551 + 539 =
  26. 26.959 − 723 =
  27. 27.930 − 604 =
  28. 28.383 + 341 =
  29. 29.690 − 579 =
  30. 30.558 − 397 =
  31. 31.502 + 618 =
  32. 32.967 − 497 =
  33. 33.564 − 315 =
  34. 34.527 + 125 =
  35. 35.599 + 373 =
  36. 36.449 + 171 =
  37. 37.205 + 664 =
  38. 38.644 − 176 =
  39. 39.538 − 431 =
  40. 40.606 − 176 =

Answer key

  1. 181
  2. 167
  3. 979
  4. 722
  5. 275
  6. 802
  7. 177
  8. 422
  9. 892
  10. 365
  11. 710
  12. 795
  13. 983
  14. 1057
  15. 898
  16. 617
  17. 714
  18. 1032
  19. 1100
  20. 311
  21. 982
  22. 1128
  23. 352
  24. 864
  25. 1090
  26. 236
  27. 326
  28. 724
  29. 111
  30. 161
  31. 1120
  32. 470
  33. 249
  34. 652
  35. 972
  36. 620
  37. 869
  38. 468
  39. 107
  40. 430

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