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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 821 · 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. 1.901 − 571 =
  2. 2.647 + 672 =
  3. 3.279 + 477 =
  4. 4.412 − 151 =
  5. 5.340 + 152 =
  6. 6.951 − 156 =
  7. 7.968 − 362 =
  8. 8.591 − 177 =
  9. 9.141 + 216 =
  10. 10.925 − 788 =
  11. 11.223 + 192 =
  12. 12.482 + 149 =
  13. 13.217 + 238 =
  14. 14.636 − 329 =
  15. 15.619 + 296 =
  16. 16.486 − 137 =
  17. 17.488 − 188 =
  18. 18.448 − 338 =
  19. 19.613 + 224 =
  20. 20.652 − 272 =
  21. 21.589 + 164 =
  22. 22.901 − 361 =
  23. 23.563 − 351 =
  24. 24.232 + 529 =
  25. 25.537 + 306 =
  26. 26.151 + 654 =
  27. 27.718 + 207 =
  28. 28.203 + 481 =
  29. 29.626 + 644 =
  30. 30.171 + 189 =
  31. 31.723 + 297 =
  32. 32.155 + 585 =
  33. 33.131 + 683 =
  34. 34.162 + 142 =
  35. 35.807 − 357 =
  36. 36.988 − 838 =
  37. 37.212 + 187 =
  38. 38.543 + 202 =
  39. 39.166 + 261 =
  40. 40.618 + 491 =

Answer key

  1. 330
  2. 1319
  3. 756
  4. 261
  5. 492
  6. 795
  7. 606
  8. 414
  9. 357
  10. 137
  11. 415
  12. 631
  13. 455
  14. 307
  15. 915
  16. 349
  17. 300
  18. 110
  19. 837
  20. 380
  21. 753
  22. 540
  23. 212
  24. 761
  25. 843
  26. 805
  27. 925
  28. 684
  29. 1270
  30. 360
  31. 1020
  32. 740
  33. 814
  34. 304
  35. 450
  36. 150
  37. 399
  38. 745
  39. 427
  40. 1109

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