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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 218 · 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. 1.766 − 476 =
  2. 2.558 − 349 =
  3. 3.750 + 214 =
  4. 4.608 − 374 =
  5. 5.431 − 135 =
  6. 6.162 + 567 =
  7. 7.196 + 529 =
  8. 8.631 + 517 =
  9. 9.511 − 404 =
  10. 10.592 − 151 =
  11. 11.789 − 617 =
  12. 12.554 − 264 =
  13. 13.299 + 635 =
  14. 14.429 + 491 =
  15. 15.805 − 229 =
  16. 16.358 + 668 =
  17. 17.129 + 448 =
  18. 18.665 − 383 =
  19. 19.433 − 173 =
  20. 20.926 − 603 =
  21. 21.437 − 283 =
  22. 22.357 + 231 =
  23. 23.566 + 186 =
  24. 24.404 + 506 =
  25. 25.947 − 269 =
  26. 26.216 + 471 =
  27. 27.708 + 176 =
  28. 28.263 + 136 =
  29. 29.563 − 199 =
  30. 30.473 + 494 =
  31. 31.711 − 349 =
  32. 32.481 + 112 =
  33. 33.552 − 171 =
  34. 34.539 + 255 =
  35. 35.294 + 114 =
  36. 36.406 + 211 =
  37. 37.610 − 367 =
  38. 38.467 + 206 =
  39. 39.162 + 613 =
  40. 40.753 + 274 =

Answer key

  1. 290
  2. 209
  3. 964
  4. 234
  5. 296
  6. 729
  7. 725
  8. 1148
  9. 107
  10. 441
  11. 172
  12. 290
  13. 934
  14. 920
  15. 576
  16. 1026
  17. 577
  18. 282
  19. 260
  20. 323
  21. 154
  22. 588
  23. 752
  24. 910
  25. 678
  26. 687
  27. 884
  28. 399
  29. 364
  30. 967
  31. 362
  32. 593
  33. 381
  34. 794
  35. 408
  36. 617
  37. 243
  38. 673
  39. 775
  40. 1027

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