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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 978 · 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. 1.312 + 135 =
  2. 2.698 + 202 =
  3. 3.480 − 221 =
  4. 4.381 + 145 =
  5. 5.713 + 481 =
  6. 6.959 − 172 =
  7. 7.403 + 589 =
  8. 8.541 − 381 =
  9. 9.251 + 491 =
  10. 10.491 + 422 =
  11. 11.705 + 349 =
  12. 12.923 − 796 =
  13. 13.894 − 234 =
  14. 14.770 + 573 =
  15. 15.543 + 403 =
  16. 16.659 − 231 =
  17. 17.153 + 393 =
  18. 18.362 + 298 =
  19. 19.279 + 355 =
  20. 20.411 + 131 =
  21. 21.450 − 157 =
  22. 22.405 + 593 =
  23. 23.470 − 313 =
  24. 24.606 + 411 =
  25. 25.566 − 361 =
  26. 26.649 − 153 =
  27. 27.482 − 311 =
  28. 28.571 − 171 =
  29. 29.708 + 292 =
  30. 30.353 + 372 =
  31. 31.297 + 339 =
  32. 32.532 + 522 =
  33. 33.531 − 401 =
  34. 34.436 − 322 =
  35. 35.409 + 328 =
  36. 36.699 − 166 =
  37. 37.550 − 216 =
  38. 38.129 + 489 =
  39. 39.680 − 173 =
  40. 40.678 − 465 =

Answer key

  1. 447
  2. 900
  3. 259
  4. 526
  5. 1194
  6. 787
  7. 992
  8. 160
  9. 742
  10. 913
  11. 1054
  12. 127
  13. 660
  14. 1343
  15. 946
  16. 428
  17. 546
  18. 660
  19. 634
  20. 542
  21. 293
  22. 998
  23. 157
  24. 1017
  25. 205
  26. 496
  27. 171
  28. 400
  29. 1000
  30. 725
  31. 636
  32. 1054
  33. 130
  34. 114
  35. 737
  36. 533
  37. 334
  38. 618
  39. 507
  40. 213

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