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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 207 · 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. 1.951 − 119 =
  2. 2.930 − 261 =
  3. 3.423 + 376 =
  4. 4.639 + 326 =
  5. 5.675 + 165 =
  6. 6.371 + 368 =
  7. 7.358 + 226 =
  8. 8.846 − 321 =
  9. 9.697 + 636 =
  10. 10.656 + 336 =
  11. 11.482 + 371 =
  12. 12.195 + 336 =
  13. 13.969 − 575 =
  14. 14.175 + 661 =
  15. 15.450 − 311 =
  16. 16.867 − 658 =
  17. 17.166 + 284 =
  18. 18.544 + 649 =
  19. 19.241 + 605 =
  20. 20.893 − 681 =
  21. 21.613 − 223 =
  22. 22.135 + 603 =
  23. 23.597 + 217 =
  24. 24.640 + 642 =
  25. 25.580 − 422 =
  26. 26.467 − 172 =
  27. 27.171 + 506 =
  28. 28.548 + 599 =
  29. 29.720 − 492 =
  30. 30.979 − 154 =
  31. 31.958 − 311 =
  32. 32.536 − 248 =
  33. 33.418 + 491 =
  34. 34.983 − 776 =
  35. 35.530 − 129 =
  36. 36.338 + 468 =
  37. 37.509 − 396 =
  38. 38.287 + 182 =
  39. 39.976 − 191 =
  40. 40.689 − 181 =

Answer key

  1. 832
  2. 669
  3. 799
  4. 965
  5. 840
  6. 739
  7. 584
  8. 525
  9. 1333
  10. 992
  11. 853
  12. 531
  13. 394
  14. 836
  15. 139
  16. 209
  17. 450
  18. 1193
  19. 846
  20. 212
  21. 390
  22. 738
  23. 814
  24. 1282
  25. 158
  26. 295
  27. 677
  28. 1147
  29. 228
  30. 825
  31. 647
  32. 288
  33. 909
  34. 207
  35. 401
  36. 806
  37. 113
  38. 469
  39. 785
  40. 508

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