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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 201 · 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. 1.527 − 249 =
  2. 2.289 + 326 =
  3. 3.179 + 275 =
  4. 4.844 − 463 =
  5. 5.454 + 352 =
  6. 6.399 + 576 =
  7. 7.481 − 221 =
  8. 8.711 − 263 =
  9. 9.897 − 372 =
  10. 10.619 − 431 =
  11. 11.608 − 129 =
  12. 12.566 − 347 =
  13. 13.580 − 207 =
  14. 14.700 − 579 =
  15. 15.282 + 237 =
  16. 16.294 + 423 =
  17. 17.743 + 163 =
  18. 18.506 + 451 =
  19. 19.693 + 271 =
  20. 20.590 + 502 =
  21. 21.406 + 616 =
  22. 22.960 − 641 =
  23. 23.736 + 115 =
  24. 24.423 + 268 =
  25. 25.761 + 681 =
  26. 26.776 + 329 =
  27. 27.475 − 204 =
  28. 28.357 + 642 =
  29. 29.435 + 387 =
  30. 30.126 + 371 =
  31. 31.163 + 501 =
  32. 32.981 − 693 =
  33. 33.423 + 596 =
  34. 34.944 − 183 =
  35. 35.820 − 463 =
  36. 36.953 − 681 =
  37. 37.650 + 113 =
  38. 38.536 − 221 =
  39. 39.941 − 517 =
  40. 40.344 + 338 =

Answer key

  1. 278
  2. 615
  3. 454
  4. 381
  5. 806
  6. 975
  7. 260
  8. 448
  9. 525
  10. 188
  11. 479
  12. 219
  13. 373
  14. 121
  15. 519
  16. 717
  17. 906
  18. 957
  19. 964
  20. 1092
  21. 1022
  22. 319
  23. 851
  24. 691
  25. 1442
  26. 1105
  27. 271
  28. 999
  29. 822
  30. 497
  31. 664
  32. 288
  33. 1019
  34. 761
  35. 357
  36. 272
  37. 763
  38. 315
  39. 424
  40. 682

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