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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 859 · 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. 1.559 − 395 =
  2. 2.717 + 291 =
  3. 3.163 + 141 =
  4. 4.289 + 112 =
  5. 5.545 − 311 =
  6. 6.862 − 349 =
  7. 7.910 − 337 =
  8. 8.515 − 215 =
  9. 9.779 + 435 =
  10. 10.441 + 473 =
  11. 11.562 − 189 =
  12. 12.415 + 227 =
  13. 13.394 + 276 =
  14. 14.569 − 223 =
  15. 15.389 + 427 =
  16. 16.897 − 468 =
  17. 17.488 − 243 =
  18. 18.498 − 186 =
  19. 19.223 + 529 =
  20. 20.192 + 494 =
  21. 21.876 − 354 =
  22. 22.437 + 633 =
  23. 23.490 − 226 =
  24. 24.563 − 414 =
  25. 25.746 + 515 =
  26. 26.457 + 612 =
  27. 27.672 − 287 =
  28. 28.428 + 568 =
  29. 29.318 + 243 =
  30. 30.561 + 413 =
  31. 31.490 − 152 =
  32. 32.548 + 516 =
  33. 33.546 − 179 =
  34. 34.223 + 669 =
  35. 35.474 − 156 =
  36. 36.331 + 325 =
  37. 37.741 − 364 =
  38. 38.721 − 542 =
  39. 39.422 + 535 =
  40. 40.592 − 277 =

Answer key

  1. 164
  2. 1008
  3. 304
  4. 401
  5. 234
  6. 513
  7. 573
  8. 300
  9. 1214
  10. 914
  11. 373
  12. 642
  13. 670
  14. 346
  15. 816
  16. 429
  17. 245
  18. 312
  19. 752
  20. 686
  21. 522
  22. 1070
  23. 264
  24. 149
  25. 1261
  26. 1069
  27. 385
  28. 996
  29. 561
  30. 974
  31. 338
  32. 1064
  33. 367
  34. 892
  35. 318
  36. 656
  37. 377
  38. 179
  39. 957
  40. 315

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