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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 906 · 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. 1.257 + 475 =
  2. 2.251 + 518 =
  3. 3.968 − 284 =
  4. 4.419 + 661 =
  5. 5.812 − 624 =
  6. 6.177 + 567 =
  7. 7.517 + 229 =
  8. 8.590 + 247 =
  9. 9.514 + 539 =
  10. 10.897 − 689 =
  11. 11.710 + 364 =
  12. 12.261 + 424 =
  13. 13.520 + 357 =
  14. 14.555 − 337 =
  15. 15.715 + 589 =
  16. 16.139 + 521 =
  17. 17.857 − 453 =
  18. 18.731 − 518 =
  19. 19.592 − 135 =
  20. 20.217 + 346 =
  21. 21.783 + 398 =
  22. 22.693 − 159 =
  23. 23.778 + 136 =
  24. 24.342 + 493 =
  25. 25.958 − 481 =
  26. 26.728 − 119 =
  27. 27.641 − 171 =
  28. 28.668 − 554 =
  29. 29.629 + 375 =
  30. 30.683 + 653 =
  31. 31.330 + 263 =
  32. 32.435 + 546 =
  33. 33.510 + 258 =
  34. 34.766 − 363 =
  35. 35.521 + 171 =
  36. 36.534 − 377 =
  37. 37.326 + 246 =
  38. 38.715 + 523 =
  39. 39.329 + 615 =
  40. 40.972 − 534 =

Answer key

  1. 732
  2. 769
  3. 684
  4. 1080
  5. 188
  6. 744
  7. 746
  8. 837
  9. 1053
  10. 208
  11. 1074
  12. 685
  13. 877
  14. 218
  15. 1304
  16. 660
  17. 404
  18. 213
  19. 457
  20. 563
  21. 1181
  22. 534
  23. 914
  24. 835
  25. 477
  26. 609
  27. 470
  28. 114
  29. 1004
  30. 1336
  31. 593
  32. 981
  33. 768
  34. 403
  35. 692
  36. 157
  37. 572
  38. 1238
  39. 944
  40. 438

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