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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 383 · 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. 1.225 + 575 =
  2. 2.655 + 605 =
  3. 3.141 + 359 =
  4. 4.434 − 242 =
  5. 5.663 − 179 =
  6. 6.713 − 599 =
  7. 7.479 − 157 =
  8. 8.511 − 191 =
  9. 9.769 − 485 =
  10. 10.421 + 577 =
  11. 11.619 − 401 =
  12. 12.227 + 368 =
  13. 13.248 + 319 =
  14. 14.522 − 185 =
  15. 15.149 + 341 =
  16. 16.737 + 467 =
  17. 17.890 − 476 =
  18. 18.673 + 166 =
  19. 19.646 + 143 =
  20. 20.892 − 322 =
  21. 21.412 − 303 =
  22. 22.401 + 275 =
  23. 23.958 − 655 =
  24. 24.929 − 698 =
  25. 25.504 + 409 =
  26. 26.412 + 498 =
  27. 27.578 − 431 =
  28. 28.135 + 628 =
  29. 29.569 + 494 =
  30. 30.596 + 428 =
  31. 31.222 + 552 =
  32. 32.882 − 467 =
  33. 33.439 − 302 =
  34. 34.952 − 403 =
  35. 35.470 − 332 =
  36. 36.822 − 191 =
  37. 37.501 − 201 =
  38. 38.456 − 311 =
  39. 39.833 − 471 =
  40. 40.612 − 453 =

Answer key

  1. 800
  2. 1260
  3. 500
  4. 192
  5. 484
  6. 114
  7. 322
  8. 320
  9. 284
  10. 998
  11. 218
  12. 595
  13. 567
  14. 337
  15. 490
  16. 1204
  17. 414
  18. 839
  19. 789
  20. 570
  21. 109
  22. 676
  23. 303
  24. 231
  25. 913
  26. 910
  27. 147
  28. 763
  29. 1063
  30. 1024
  31. 774
  32. 415
  33. 137
  34. 549
  35. 138
  36. 631
  37. 300
  38. 145
  39. 362
  40. 159

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