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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 749 · 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. 1.421 + 665 =
  2. 2.532 − 204 =
  3. 3.491 − 202 =
  4. 4.959 − 411 =
  5. 5.849 − 648 =
  6. 6.758 + 395 =
  7. 7.240 + 204 =
  8. 8.875 − 168 =
  9. 9.554 − 226 =
  10. 10.867 − 221 =
  11. 11.659 − 512 =
  12. 12.902 − 228 =
  13. 13.904 − 243 =
  14. 14.753 − 651 =
  15. 15.539 + 361 =
  16. 16.662 + 401 =
  17. 17.393 + 494 =
  18. 18.889 − 684 =
  19. 19.552 − 311 =
  20. 20.574 + 181 =
  21. 21.332 + 539 =
  22. 22.556 + 577 =
  23. 23.932 − 417 =
  24. 24.426 − 265 =
  25. 25.675 − 267 =
  26. 26.472 − 282 =
  27. 27.520 − 203 =
  28. 28.433 − 214 =
  29. 29.272 + 435 =
  30. 30.777 − 645 =
  31. 31.853 − 251 =
  32. 32.298 + 385 =
  33. 33.638 − 135 =
  34. 34.970 − 674 =
  35. 35.658 − 508 =
  36. 36.704 − 268 =
  37. 37.482 + 374 =
  38. 38.952 − 841 =
  39. 39.466 − 121 =
  40. 40.532 − 167 =

Answer key

  1. 1086
  2. 328
  3. 289
  4. 548
  5. 201
  6. 1153
  7. 444
  8. 707
  9. 328
  10. 646
  11. 147
  12. 674
  13. 661
  14. 102
  15. 900
  16. 1063
  17. 887
  18. 205
  19. 241
  20. 755
  21. 871
  22. 1133
  23. 515
  24. 161
  25. 408
  26. 190
  27. 317
  28. 219
  29. 707
  30. 132
  31. 602
  32. 683
  33. 503
  34. 296
  35. 150
  36. 436
  37. 856
  38. 111
  39. 345
  40. 365

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