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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 489 · 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. 1.184 + 195 =
  2. 2.756 − 142 =
  3. 3.778 − 254 =
  4. 4.554 − 324 =
  5. 5.133 + 588 =
  6. 6.828 − 697 =
  7. 7.576 + 148 =
  8. 8.493 − 381 =
  9. 9.619 + 141 =
  10. 10.166 + 331 =
  11. 11.167 + 504 =
  12. 12.299 + 186 =
  13. 13.175 + 246 =
  14. 14.784 − 403 =
  15. 15.648 − 309 =
  16. 16.280 + 362 =
  17. 17.786 − 434 =
  18. 18.621 − 516 =
  19. 19.381 + 596 =
  20. 20.968 − 569 =
  21. 21.230 + 512 =
  22. 22.600 + 354 =
  23. 23.754 − 454 =
  24. 24.804 − 152 =
  25. 25.354 + 211 =
  26. 26.763 + 154 =
  27. 27.333 + 688 =
  28. 28.423 + 585 =
  29. 29.609 − 161 =
  30. 30.657 + 526 =
  31. 31.599 + 391 =
  32. 32.133 + 553 =
  33. 33.830 − 151 =
  34. 34.326 + 677 =
  35. 35.626 + 335 =
  36. 36.661 − 499 =
  37. 37.622 + 273 =
  38. 38.493 − 348 =
  39. 39.235 + 175 =
  40. 40.737 + 593 =

Answer key

  1. 379
  2. 614
  3. 524
  4. 230
  5. 721
  6. 131
  7. 724
  8. 112
  9. 760
  10. 497
  11. 671
  12. 485
  13. 421
  14. 381
  15. 339
  16. 642
  17. 352
  18. 105
  19. 977
  20. 399
  21. 742
  22. 954
  23. 300
  24. 652
  25. 565
  26. 917
  27. 1021
  28. 1008
  29. 448
  30. 1183
  31. 990
  32. 686
  33. 679
  34. 1003
  35. 961
  36. 162
  37. 895
  38. 145
  39. 410
  40. 1330

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