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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 98 · 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. 1.636 − 503 =
  2. 2.745 + 684 =
  3. 3.605 + 575 =
  4. 4.259 + 457 =
  5. 5.491 − 144 =
  6. 6.316 + 562 =
  7. 7.358 + 151 =
  8. 8.918 − 464 =
  9. 9.408 + 359 =
  10. 10.776 − 624 =
  11. 11.395 + 408 =
  12. 12.476 + 224 =
  13. 13.278 + 415 =
  14. 14.709 + 481 =
  15. 15.628 − 508 =
  16. 16.601 − 215 =
  17. 17.689 + 522 =
  18. 18.295 + 624 =
  19. 19.308 + 524 =
  20. 20.855 − 594 =
  21. 21.273 + 171 =
  22. 22.492 − 357 =
  23. 23.655 − 511 =
  24. 24.670 + 166 =
  25. 25.636 + 173 =
  26. 26.989 − 159 =
  27. 27.635 + 339 =
  28. 28.837 − 463 =
  29. 29.346 + 603 =
  30. 30.801 − 229 =
  31. 31.416 + 313 =
  32. 32.696 + 234 =
  33. 33.427 + 653 =
  34. 34.744 + 231 =
  35. 35.314 + 371 =
  36. 36.435 − 214 =
  37. 37.782 + 306 =
  38. 38.633 + 674 =
  39. 39.634 − 218 =
  40. 40.937 − 668 =

Answer key

  1. 133
  2. 1429
  3. 1180
  4. 716
  5. 347
  6. 878
  7. 509
  8. 454
  9. 767
  10. 152
  11. 803
  12. 700
  13. 693
  14. 1190
  15. 120
  16. 386
  17. 1211
  18. 919
  19. 832
  20. 261
  21. 444
  22. 135
  23. 144
  24. 836
  25. 809
  26. 830
  27. 974
  28. 374
  29. 949
  30. 572
  31. 729
  32. 930
  33. 1080
  34. 975
  35. 685
  36. 221
  37. 1088
  38. 1307
  39. 416
  40. 269

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