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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 933 · 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. 1.498 − 191 =
  2. 2.264 + 351 =
  3. 3.169 + 373 =
  4. 4.306 + 394 =
  5. 5.797 − 227 =
  6. 6.658 + 387 =
  7. 7.378 + 431 =
  8. 8.870 − 645 =
  9. 9.732 + 505 =
  10. 10.968 − 367 =
  11. 11.602 + 431 =
  12. 12.521 + 394 =
  13. 13.662 − 232 =
  14. 14.350 + 123 =
  15. 15.469 + 648 =
  16. 16.410 + 412 =
  17. 17.442 + 501 =
  18. 18.660 + 534 =
  19. 19.322 + 135 =
  20. 20.332 + 473 =
  21. 21.595 − 379 =
  22. 22.654 + 613 =
  23. 23.948 − 442 =
  24. 24.664 − 444 =
  25. 25.629 − 201 =
  26. 26.324 + 153 =
  27. 27.465 + 483 =
  28. 28.296 + 173 =
  29. 29.173 + 568 =
  30. 30.204 + 615 =
  31. 31.578 − 327 =
  32. 32.592 − 173 =
  33. 33.765 + 241 =
  34. 34.748 + 291 =
  35. 35.642 − 317 =
  36. 36.212 + 413 =
  37. 37.502 − 181 =
  38. 38.349 + 508 =
  39. 39.151 + 127 =
  40. 40.681 − 181 =

Answer key

  1. 307
  2. 615
  3. 542
  4. 700
  5. 570
  6. 1045
  7. 809
  8. 225
  9. 1237
  10. 601
  11. 1033
  12. 915
  13. 430
  14. 473
  15. 1117
  16. 822
  17. 943
  18. 1194
  19. 457
  20. 805
  21. 216
  22. 1267
  23. 506
  24. 220
  25. 428
  26. 477
  27. 948
  28. 469
  29. 741
  30. 819
  31. 251
  32. 419
  33. 1006
  34. 1039
  35. 325
  36. 625
  37. 321
  38. 857
  39. 278
  40. 500

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