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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 677 · 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. 1.333 + 171 =
  2. 2.229 + 619 =
  3. 3.448 + 191 =
  4. 4.915 − 176 =
  5. 5.551 − 145 =
  6. 6.684 + 343 =
  7. 7.687 − 207 =
  8. 8.850 − 291 =
  9. 9.775 − 155 =
  10. 10.729 − 311 =
  11. 11.529 − 288 =
  12. 12.638 + 611 =
  13. 13.539 + 681 =
  14. 14.769 − 664 =
  15. 15.442 + 391 =
  16. 16.644 − 538 =
  17. 17.277 + 601 =
  18. 18.975 − 581 =
  19. 19.501 + 191 =
  20. 20.157 + 244 =
  21. 21.480 − 187 =
  22. 22.748 − 288 =
  23. 23.724 + 394 =
  24. 24.869 − 464 =
  25. 25.565 − 352 =
  26. 26.285 + 322 =
  27. 27.811 − 315 =
  28. 28.751 + 674 =
  29. 29.561 − 309 =
  30. 30.274 + 382 =
  31. 31.829 − 278 =
  32. 32.507 + 324 =
  33. 33.495 − 358 =
  34. 34.527 + 279 =
  35. 35.967 − 657 =
  36. 36.646 + 298 =
  37. 37.938 − 401 =
  38. 38.853 − 328 =
  39. 39.504 − 265 =
  40. 40.300 + 221 =

Answer key

  1. 504
  2. 848
  3. 639
  4. 739
  5. 406
  6. 1027
  7. 480
  8. 559
  9. 620
  10. 418
  11. 241
  12. 1249
  13. 1220
  14. 105
  15. 833
  16. 106
  17. 878
  18. 394
  19. 692
  20. 401
  21. 293
  22. 460
  23. 1118
  24. 405
  25. 213
  26. 607
  27. 496
  28. 1425
  29. 252
  30. 656
  31. 551
  32. 831
  33. 137
  34. 806
  35. 310
  36. 944
  37. 537
  38. 525
  39. 239
  40. 521

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