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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 896 · 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. 1.565 − 399 =
  2. 2.948 − 654 =
  3. 3.479 − 203 =
  4. 4.518 − 167 =
  5. 5.228 + 419 =
  6. 6.849 − 587 =
  7. 7.419 + 411 =
  8. 8.617 − 368 =
  9. 9.601 + 348 =
  10. 10.674 + 357 =
  11. 11.334 + 207 =
  12. 12.976 − 243 =
  13. 13.303 + 438 =
  14. 14.333 + 452 =
  15. 15.839 − 125 =
  16. 16.609 + 467 =
  17. 17.803 − 581 =
  18. 18.844 − 183 =
  19. 19.537 + 244 =
  20. 20.267 + 301 =
  21. 21.758 − 187 =
  22. 22.475 − 323 =
  23. 23.423 + 603 =
  24. 24.700 − 227 =
  25. 25.661 + 277 =
  26. 26.774 + 161 =
  27. 27.752 − 595 =
  28. 28.556 − 113 =
  29. 29.497 − 175 =
  30. 30.881 − 185 =
  31. 31.894 − 652 =
  32. 32.831 − 157 =
  33. 33.587 + 623 =
  34. 34.482 + 164 =
  35. 35.186 + 249 =
  36. 36.398 + 385 =
  37. 37.742 + 659 =
  38. 38.585 − 381 =
  39. 39.957 − 571 =
  40. 40.750 + 668 =

Answer key

  1. 166
  2. 294
  3. 276
  4. 351
  5. 647
  6. 262
  7. 830
  8. 249
  9. 949
  10. 1031
  11. 541
  12. 733
  13. 741
  14. 785
  15. 714
  16. 1076
  17. 222
  18. 661
  19. 781
  20. 568
  21. 571
  22. 152
  23. 1026
  24. 473
  25. 938
  26. 935
  27. 157
  28. 443
  29. 322
  30. 696
  31. 242
  32. 674
  33. 1210
  34. 646
  35. 435
  36. 783
  37. 1401
  38. 204
  39. 386
  40. 1418

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