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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 112 · 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. 1.687 − 286 =
  2. 2.558 − 456 =
  3. 3.459 − 185 =
  4. 4.123 + 363 =
  5. 5.972 − 815 =
  6. 6.986 − 264 =
  7. 7.295 + 112 =
  8. 8.361 + 627 =
  9. 9.315 + 463 =
  10. 10.466 + 578 =
  11. 11.458 + 181 =
  12. 12.941 − 261 =
  13. 13.903 − 168 =
  14. 14.478 + 554 =
  15. 15.663 − 272 =
  16. 16.461 − 338 =
  17. 17.927 − 118 =
  18. 18.892 − 788 =
  19. 19.316 + 141 =
  20. 20.533 + 461 =
  21. 21.666 + 378 =
  22. 22.674 + 509 =
  23. 23.568 − 192 =
  24. 24.412 − 124 =
  25. 25.539 + 497 =
  26. 26.812 − 547 =
  27. 27.483 + 245 =
  28. 28.418 − 239 =
  29. 29.258 + 122 =
  30. 30.297 + 373 =
  31. 31.567 + 592 =
  32. 32.245 + 368 =
  33. 33.471 + 341 =
  34. 34.954 − 122 =
  35. 35.864 − 329 =
  36. 36.646 − 518 =
  37. 37.658 − 261 =
  38. 38.497 − 171 =
  39. 39.403 + 132 =
  40. 40.228 + 488 =

Answer key

  1. 401
  2. 102
  3. 274
  4. 486
  5. 157
  6. 722
  7. 407
  8. 988
  9. 778
  10. 1044
  11. 639
  12. 680
  13. 735
  14. 1032
  15. 391
  16. 123
  17. 809
  18. 104
  19. 457
  20. 994
  21. 1044
  22. 1183
  23. 376
  24. 288
  25. 1036
  26. 265
  27. 728
  28. 179
  29. 380
  30. 670
  31. 1159
  32. 613
  33. 812
  34. 832
  35. 535
  36. 128
  37. 397
  38. 326
  39. 535
  40. 716

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