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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 364 · 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. 1.245 + 636 =
  2. 2.696 − 595 =
  3. 3.371 + 117 =
  4. 4.327 + 431 =
  5. 5.721 + 259 =
  6. 6.339 + 276 =
  7. 7.596 − 335 =
  8. 8.697 − 538 =
  9. 9.589 − 114 =
  10. 10.447 + 433 =
  11. 11.695 + 341 =
  12. 12.464 − 345 =
  13. 13.841 − 375 =
  14. 14.455 − 183 =
  15. 15.135 + 686 =
  16. 16.659 + 363 =
  17. 17.515 − 369 =
  18. 18.519 + 184 =
  19. 19.720 + 226 =
  20. 20.500 + 593 =
  21. 21.874 − 751 =
  22. 22.820 − 635 =
  23. 23.587 + 643 =
  24. 24.698 − 258 =
  25. 25.781 + 491 =
  26. 26.479 − 221 =
  27. 27.503 − 348 =
  28. 28.743 − 119 =
  29. 29.656 − 525 =
  30. 30.455 + 316 =
  31. 31.649 + 629 =
  32. 32.530 + 277 =
  33. 33.557 + 288 =
  34. 34.443 + 155 =
  35. 35.705 − 366 =
  36. 36.845 − 328 =
  37. 37.174 + 447 =
  38. 38.735 + 431 =
  39. 39.881 − 517 =
  40. 40.438 − 185 =

Answer key

  1. 881
  2. 101
  3. 488
  4. 758
  5. 980
  6. 615
  7. 261
  8. 159
  9. 475
  10. 880
  11. 1036
  12. 119
  13. 466
  14. 272
  15. 821
  16. 1022
  17. 146
  18. 703
  19. 946
  20. 1093
  21. 123
  22. 185
  23. 1230
  24. 440
  25. 1272
  26. 258
  27. 155
  28. 624
  29. 131
  30. 771
  31. 1278
  32. 807
  33. 845
  34. 598
  35. 339
  36. 517
  37. 621
  38. 1166
  39. 364
  40. 253

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