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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 830 · 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. 1.759 − 297 =
  2. 2.432 + 408 =
  3. 3.562 − 131 =
  4. 4.514 + 462 =
  5. 5.405 + 688 =
  6. 6.447 + 278 =
  7. 7.744 − 519 =
  8. 8.533 − 307 =
  9. 9.384 + 134 =
  10. 10.818 − 657 =
  11. 11.167 + 233 =
  12. 12.682 + 121 =
  13. 13.699 − 475 =
  14. 14.611 + 119 =
  15. 15.918 − 232 =
  16. 16.416 + 284 =
  17. 17.732 − 361 =
  18. 18.421 − 271 =
  19. 19.612 − 451 =
  20. 20.816 − 252 =
  21. 21.206 + 231 =
  22. 22.180 + 646 =
  23. 23.658 + 294 =
  24. 24.239 + 594 =
  25. 25.766 + 572 =
  26. 26.194 + 515 =
  27. 27.500 − 207 =
  28. 28.867 − 757 =
  29. 29.629 − 294 =
  30. 30.273 + 353 =
  31. 31.393 + 329 =
  32. 32.637 − 377 =
  33. 33.192 + 609 =
  34. 34.188 + 552 =
  35. 35.526 − 391 =
  36. 36.463 − 333 =
  37. 37.504 − 359 =
  38. 38.454 + 329 =
  39. 39.576 − 335 =
  40. 40.654 + 211 =

Answer key

  1. 462
  2. 840
  3. 431
  4. 976
  5. 1093
  6. 725
  7. 225
  8. 226
  9. 518
  10. 161
  11. 400
  12. 803
  13. 224
  14. 730
  15. 686
  16. 700
  17. 371
  18. 150
  19. 161
  20. 564
  21. 437
  22. 826
  23. 952
  24. 833
  25. 1338
  26. 709
  27. 293
  28. 110
  29. 335
  30. 626
  31. 722
  32. 260
  33. 801
  34. 740
  35. 135
  36. 130
  37. 145
  38. 783
  39. 241
  40. 865

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