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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 367 · 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. 1.471 + 326 =
  2. 2.545 − 246 =
  3. 3.648 + 273 =
  4. 4.213 + 645 =
  5. 5.815 − 175 =
  6. 6.521 − 176 =
  7. 7.716 + 279 =
  8. 8.748 + 332 =
  9. 9.898 − 293 =
  10. 10.964 − 232 =
  11. 11.419 + 348 =
  12. 12.655 − 142 =
  13. 13.325 + 481 =
  14. 14.740 + 557 =
  15. 15.577 − 461 =
  16. 16.284 + 689 =
  17. 17.437 + 507 =
  18. 18.565 − 181 =
  19. 19.458 + 191 =
  20. 20.618 + 203 =
  21. 21.340 + 213 =
  22. 22.398 + 246 =
  23. 23.416 − 236 =
  24. 24.487 − 258 =
  25. 25.366 + 557 =
  26. 26.684 − 165 =
  27. 27.640 + 199 =
  28. 28.662 − 559 =
  29. 29.488 + 242 =
  30. 30.473 − 141 =
  31. 31.365 + 369 =
  32. 32.937 − 291 =
  33. 33.303 + 279 =
  34. 34.617 − 371 =
  35. 35.814 − 451 =
  36. 36.255 + 534 =
  37. 37.514 − 347 =
  38. 38.291 + 577 =
  39. 39.295 + 415 =
  40. 40.508 − 216 =

Answer key

  1. 797
  2. 299
  3. 921
  4. 858
  5. 640
  6. 345
  7. 995
  8. 1080
  9. 605
  10. 732
  11. 767
  12. 513
  13. 806
  14. 1297
  15. 116
  16. 973
  17. 944
  18. 384
  19. 649
  20. 821
  21. 553
  22. 644
  23. 180
  24. 229
  25. 923
  26. 519
  27. 839
  28. 103
  29. 730
  30. 332
  31. 734
  32. 646
  33. 582
  34. 246
  35. 363
  36. 789
  37. 167
  38. 868
  39. 710
  40. 292

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