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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 642 · 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. 1.908 − 389 =
  2. 2.919 − 745 =
  3. 3.661 − 131 =
  4. 4.654 + 464 =
  5. 5.426 − 218 =
  6. 6.883 − 738 =
  7. 7.309 + 661 =
  8. 8.534 − 316 =
  9. 9.179 + 356 =
  10. 10.420 − 229 =
  11. 11.259 + 441 =
  12. 12.190 + 326 =
  13. 13.160 + 682 =
  14. 14.222 + 216 =
  15. 15.683 − 231 =
  16. 16.569 + 175 =
  17. 17.465 + 419 =
  18. 18.138 + 271 =
  19. 19.729 + 329 =
  20. 20.816 − 403 =
  21. 21.502 + 404 =
  22. 22.687 − 147 =
  23. 23.956 − 181 =
  24. 24.130 + 119 =
  25. 25.476 − 291 =
  26. 26.234 + 638 =
  27. 27.747 − 217 =
  28. 28.745 − 634 =
  29. 29.697 + 294 =
  30. 30.449 + 617 =
  31. 31.429 − 301 =
  32. 32.463 + 244 =
  33. 33.648 + 118 =
  34. 34.924 − 723 =
  35. 35.949 − 373 =
  36. 36.915 − 181 =
  37. 37.788 − 263 =
  38. 38.351 + 564 =
  39. 39.543 + 532 =
  40. 40.392 + 685 =

Answer key

  1. 519
  2. 174
  3. 530
  4. 1118
  5. 208
  6. 145
  7. 970
  8. 218
  9. 535
  10. 191
  11. 700
  12. 516
  13. 842
  14. 438
  15. 452
  16. 744
  17. 884
  18. 409
  19. 1058
  20. 413
  21. 906
  22. 540
  23. 775
  24. 249
  25. 185
  26. 872
  27. 530
  28. 111
  29. 991
  30. 1066
  31. 128
  32. 707
  33. 766
  34. 201
  35. 576
  36. 734
  37. 525
  38. 915
  39. 1075
  40. 1077

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