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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 115 · 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. 1.986 − 127 =
  2. 2.538 − 233 =
  3. 3.653 + 579 =
  4. 4.390 + 217 =
  5. 5.646 − 427 =
  6. 6.270 + 201 =
  7. 7.611 + 253 =
  8. 8.189 + 401 =
  9. 9.647 + 446 =
  10. 10.776 + 203 =
  11. 11.799 − 579 =
  12. 12.516 − 318 =
  13. 13.375 + 221 =
  14. 14.711 − 495 =
  15. 15.606 + 682 =
  16. 16.590 − 418 =
  17. 17.470 + 588 =
  18. 18.847 − 401 =
  19. 19.386 + 414 =
  20. 20.258 + 685 =
  21. 21.962 − 801 =
  22. 22.769 + 294 =
  23. 23.257 + 171 =
  24. 24.517 + 152 =
  25. 25.519 − 226 =
  26. 26.489 − 144 =
  27. 27.387 + 607 =
  28. 28.434 + 415 =
  29. 29.628 + 133 =
  30. 30.675 + 145 =
  31. 31.420 + 485 =
  32. 32.754 − 449 =
  33. 33.877 − 244 =
  34. 34.659 + 652 =
  35. 35.692 + 369 =
  36. 36.954 − 515 =
  37. 37.749 + 307 =
  38. 38.741 + 471 =
  39. 39.579 − 443 =
  40. 40.670 − 314 =

Answer key

  1. 859
  2. 305
  3. 1232
  4. 607
  5. 219
  6. 471
  7. 864
  8. 590
  9. 1093
  10. 979
  11. 220
  12. 198
  13. 596
  14. 216
  15. 1288
  16. 172
  17. 1058
  18. 446
  19. 800
  20. 943
  21. 161
  22. 1063
  23. 428
  24. 669
  25. 293
  26. 345
  27. 994
  28. 849
  29. 761
  30. 820
  31. 905
  32. 305
  33. 633
  34. 1311
  35. 1061
  36. 439
  37. 1056
  38. 1212
  39. 136
  40. 356

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