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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 180 · 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. 1.742 − 625 =
  2. 2.184 + 154 =
  3. 3.197 + 673 =
  4. 4.312 + 303 =
  5. 5.221 + 201 =
  6. 6.167 + 292 =
  7. 7.247 + 651 =
  8. 8.658 − 308 =
  9. 9.766 + 438 =
  10. 10.379 + 498 =
  11. 11.550 − 261 =
  12. 12.735 + 268 =
  13. 13.482 − 238 =
  14. 14.511 − 221 =
  15. 15.443 − 168 =
  16. 16.455 + 636 =
  17. 17.655 + 148 =
  18. 18.632 + 555 =
  19. 19.484 + 281 =
  20. 20.293 + 361 =
  21. 21.592 + 638 =
  22. 22.974 − 343 =
  23. 23.783 + 409 =
  24. 24.317 + 366 =
  25. 25.492 + 523 =
  26. 26.757 − 221 =
  27. 27.495 − 155 =
  28. 28.247 + 467 =
  29. 29.495 − 151 =
  30. 30.521 + 582 =
  31. 31.666 + 353 =
  32. 32.318 + 147 =
  33. 33.777 − 298 =
  34. 34.617 − 445 =
  35. 35.569 + 491 =
  36. 36.777 − 312 =
  37. 37.237 + 399 =
  38. 38.763 + 201 =
  39. 39.229 + 637 =
  40. 40.575 − 344 =

Answer key

  1. 117
  2. 338
  3. 870
  4. 615
  5. 422
  6. 459
  7. 898
  8. 350
  9. 1204
  10. 877
  11. 289
  12. 1003
  13. 244
  14. 290
  15. 275
  16. 1091
  17. 803
  18. 1187
  19. 765
  20. 654
  21. 1230
  22. 631
  23. 1192
  24. 683
  25. 1015
  26. 536
  27. 340
  28. 714
  29. 344
  30. 1103
  31. 1019
  32. 465
  33. 479
  34. 172
  35. 1060
  36. 465
  37. 636
  38. 964
  39. 866
  40. 231

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