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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 491 · 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. 1.576 − 128 =
  2. 2.644 − 297 =
  3. 3.740 − 628 =
  4. 4.641 + 559 =
  5. 5.598 + 334 =
  6. 6.477 + 449 =
  7. 7.149 + 661 =
  8. 8.593 − 132 =
  9. 9.824 − 653 =
  10. 10.860 − 571 =
  11. 11.592 − 137 =
  12. 12.603 − 468 =
  13. 13.982 − 504 =
  14. 14.771 − 279 =
  15. 15.807 − 633 =
  16. 16.551 − 265 =
  17. 17.226 + 638 =
  18. 18.912 − 262 =
  19. 19.281 + 358 =
  20. 20.925 − 115 =
  21. 21.947 − 504 =
  22. 22.919 − 164 =
  23. 23.718 − 284 =
  24. 24.743 − 284 =
  25. 25.601 + 174 =
  26. 26.654 − 512 =
  27. 27.159 + 331 =
  28. 28.641 + 324 =
  29. 29.398 + 411 =
  30. 30.588 + 252 =
  31. 31.524 − 217 =
  32. 32.870 − 511 =
  33. 33.408 + 171 =
  34. 34.774 − 263 =
  35. 35.659 − 205 =
  36. 36.289 + 686 =
  37. 37.720 + 531 =
  38. 38.524 + 285 =
  39. 39.468 − 152 =
  40. 40.743 − 505 =

Answer key

  1. 448
  2. 347
  3. 112
  4. 1200
  5. 932
  6. 926
  7. 810
  8. 461
  9. 171
  10. 289
  11. 455
  12. 135
  13. 478
  14. 492
  15. 174
  16. 286
  17. 864
  18. 650
  19. 639
  20. 810
  21. 443
  22. 755
  23. 434
  24. 459
  25. 775
  26. 142
  27. 490
  28. 965
  29. 809
  30. 840
  31. 307
  32. 359
  33. 579
  34. 511
  35. 454
  36. 975
  37. 1251
  38. 809
  39. 316
  40. 238

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