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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 613 · 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. 1.268 + 438 =
  2. 2.422 − 258 =
  3. 3.858 − 534 =
  4. 4.177 + 162 =
  5. 5.693 − 417 =
  6. 6.241 + 651 =
  7. 7.741 + 281 =
  8. 8.486 − 335 =
  9. 9.613 − 131 =
  10. 10.624 + 297 =
  11. 11.455 − 268 =
  12. 12.455 − 285 =
  13. 13.467 + 589 =
  14. 14.670 + 167 =
  15. 15.762 − 277 =
  16. 16.175 + 322 =
  17. 17.253 + 541 =
  18. 18.524 − 149 =
  19. 19.605 + 311 =
  20. 20.610 + 496 =
  21. 21.334 + 489 =
  22. 22.564 + 635 =
  23. 23.444 − 125 =
  24. 24.503 − 168 =
  25. 25.921 − 431 =
  26. 26.350 + 311 =
  27. 27.466 + 331 =
  28. 28.490 − 221 =
  29. 29.967 − 328 =
  30. 30.750 − 213 =
  31. 31.577 − 445 =
  32. 32.785 − 337 =
  33. 33.793 − 371 =
  34. 34.866 − 638 =
  35. 35.856 − 418 =
  36. 36.382 + 532 =
  37. 37.193 + 456 =
  38. 38.654 − 189 =
  39. 39.336 + 536 =
  40. 40.715 + 396 =

Answer key

  1. 706
  2. 164
  3. 324
  4. 339
  5. 276
  6. 892
  7. 1022
  8. 151
  9. 482
  10. 921
  11. 187
  12. 170
  13. 1056
  14. 837
  15. 485
  16. 497
  17. 794
  18. 375
  19. 916
  20. 1106
  21. 823
  22. 1199
  23. 319
  24. 335
  25. 490
  26. 661
  27. 797
  28. 269
  29. 639
  30. 537
  31. 132
  32. 448
  33. 422
  34. 228
  35. 438
  36. 914
  37. 649
  38. 465
  39. 872
  40. 1111

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