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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 738 · 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. 1.890 − 536 =
  2. 2.488 − 387 =
  3. 3.362 + 357 =
  4. 4.493 − 382 =
  5. 5.510 + 671 =
  6. 6.549 − 427 =
  7. 7.455 + 651 =
  8. 8.637 + 159 =
  9. 9.332 + 572 =
  10. 10.985 − 603 =
  11. 11.292 + 497 =
  12. 12.566 − 301 =
  13. 13.347 + 687 =
  14. 14.187 + 303 =
  15. 15.267 + 141 =
  16. 16.456 + 333 =
  17. 17.670 + 457 =
  18. 18.758 + 178 =
  19. 19.714 − 268 =
  20. 20.450 − 286 =
  21. 21.760 − 291 =
  22. 22.427 + 422 =
  23. 23.970 − 332 =
  24. 24.720 + 161 =
  25. 25.179 + 557 =
  26. 26.923 − 543 =
  27. 27.594 − 149 =
  28. 28.984 − 163 =
  29. 29.646 + 519 =
  30. 30.235 + 121 =
  31. 31.300 + 201 =
  32. 32.497 − 338 =
  33. 33.588 − 486 =
  34. 34.440 − 189 =
  35. 35.372 + 122 =
  36. 36.446 + 616 =
  37. 37.480 − 335 =
  38. 38.909 − 286 =
  39. 39.457 − 145 =
  40. 40.580 − 217 =

Answer key

  1. 354
  2. 101
  3. 719
  4. 111
  5. 1181
  6. 122
  7. 1106
  8. 796
  9. 904
  10. 382
  11. 789
  12. 265
  13. 1034
  14. 490
  15. 408
  16. 789
  17. 1127
  18. 936
  19. 446
  20. 164
  21. 469
  22. 849
  23. 638
  24. 881
  25. 736
  26. 380
  27. 445
  28. 821
  29. 1165
  30. 356
  31. 501
  32. 159
  33. 102
  34. 251
  35. 494
  36. 1062
  37. 145
  38. 623
  39. 312
  40. 363

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