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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 888 · 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. 1.428 + 597 =
  2. 2.526 + 623 =
  3. 3.577 + 176 =
  4. 4.682 + 579 =
  5. 5.278 + 272 =
  6. 6.721 − 428 =
  7. 7.599 + 412 =
  8. 8.961 − 464 =
  9. 9.609 + 657 =
  10. 10.256 + 118 =
  11. 11.393 + 612 =
  12. 12.571 − 117 =
  13. 13.257 + 279 =
  14. 14.770 + 316 =
  15. 15.647 − 452 =
  16. 16.654 − 357 =
  17. 17.756 − 295 =
  18. 18.728 + 114 =
  19. 19.566 − 178 =
  20. 20.550 + 485 =
  21. 21.819 − 551 =
  22. 22.385 + 456 =
  23. 23.435 − 218 =
  24. 24.434 − 113 =
  25. 25.524 − 421 =
  26. 26.866 − 701 =
  27. 27.626 + 371 =
  28. 28.467 + 309 =
  29. 29.910 − 186 =
  30. 30.664 + 257 =
  31. 31.251 + 138 =
  32. 32.348 + 176 =
  33. 33.584 − 112 =
  34. 34.207 + 222 =
  35. 35.688 + 292 =
  36. 36.576 + 292 =
  37. 37.138 + 482 =
  38. 38.413 + 275 =
  39. 39.168 + 286 =
  40. 40.751 − 171 =

Answer key

  1. 1025
  2. 1149
  3. 753
  4. 1261
  5. 550
  6. 293
  7. 1011
  8. 497
  9. 1266
  10. 374
  11. 1005
  12. 454
  13. 536
  14. 1086
  15. 195
  16. 297
  17. 461
  18. 842
  19. 388
  20. 1035
  21. 268
  22. 841
  23. 217
  24. 321
  25. 103
  26. 165
  27. 997
  28. 776
  29. 724
  30. 921
  31. 389
  32. 524
  33. 472
  34. 429
  35. 980
  36. 868
  37. 620
  38. 688
  39. 454
  40. 580

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