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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 873 · 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. 1.342 + 576 =
  2. 2.541 + 211 =
  3. 3.388 + 355 =
  4. 4.637 − 334 =
  5. 5.674 + 236 =
  6. 6.678 − 578 =
  7. 7.625 − 461 =
  8. 8.512 + 131 =
  9. 9.692 + 491 =
  10. 10.838 − 678 =
  11. 11.141 + 339 =
  12. 12.525 + 607 =
  13. 13.589 + 606 =
  14. 14.673 − 484 =
  15. 15.860 − 168 =
  16. 16.227 + 558 =
  17. 17.570 − 366 =
  18. 18.931 − 577 =
  19. 19.283 + 601 =
  20. 20.523 + 279 =
  21. 21.887 − 513 =
  22. 22.476 + 484 =
  23. 23.480 + 635 =
  24. 24.475 − 327 =
  25. 25.841 − 618 =
  26. 26.696 + 475 =
  27. 27.748 − 597 =
  28. 28.437 + 585 =
  29. 29.748 − 333 =
  30. 30.615 + 391 =
  31. 31.715 − 348 =
  32. 32.766 − 325 =
  33. 33.451 − 232 =
  34. 34.724 − 181 =
  35. 35.211 + 505 =
  36. 36.692 − 592 =
  37. 37.281 + 458 =
  38. 38.163 + 267 =
  39. 39.457 − 347 =
  40. 40.496 − 283 =

Answer key

  1. 918
  2. 752
  3. 743
  4. 303
  5. 910
  6. 100
  7. 164
  8. 643
  9. 1183
  10. 160
  11. 480
  12. 1132
  13. 1195
  14. 189
  15. 692
  16. 785
  17. 204
  18. 354
  19. 884
  20. 802
  21. 374
  22. 960
  23. 1115
  24. 148
  25. 223
  26. 1171
  27. 151
  28. 1022
  29. 415
  30. 1006
  31. 367
  32. 441
  33. 219
  34. 543
  35. 716
  36. 100
  37. 739
  38. 430
  39. 110
  40. 213

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