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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 381 · 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. 1.644 + 461 =
  2. 2.603 + 271 =
  3. 3.526 + 531 =
  4. 4.690 − 581 =
  5. 5.524 − 326 =
  6. 6.790 − 248 =
  7. 7.790 − 611 =
  8. 8.533 − 276 =
  9. 9.338 + 606 =
  10. 10.766 − 288 =
  11. 11.725 + 436 =
  12. 12.475 + 245 =
  13. 13.559 − 257 =
  14. 14.986 − 293 =
  15. 15.802 − 417 =
  16. 16.482 + 249 =
  17. 17.441 − 156 =
  18. 18.267 + 477 =
  19. 19.795 − 631 =
  20. 20.552 + 372 =
  21. 21.163 + 161 =
  22. 22.706 + 465 =
  23. 23.569 + 291 =
  24. 24.431 + 581 =
  25. 25.507 − 157 =
  26. 26.555 + 644 =
  27. 27.480 − 177 =
  28. 28.199 + 612 =
  29. 29.493 − 342 =
  30. 30.743 + 194 =
  31. 31.501 − 211 =
  32. 32.781 − 626 =
  33. 33.282 + 452 =
  34. 34.269 + 585 =
  35. 35.658 + 633 =
  36. 36.276 + 311 =
  37. 37.683 − 337 =
  38. 38.962 − 342 =
  39. 39.415 + 621 =
  40. 40.294 + 179 =

Answer key

  1. 1105
  2. 874
  3. 1057
  4. 109
  5. 198
  6. 542
  7. 179
  8. 257
  9. 944
  10. 478
  11. 1161
  12. 720
  13. 302
  14. 693
  15. 385
  16. 731
  17. 285
  18. 744
  19. 164
  20. 924
  21. 324
  22. 1171
  23. 860
  24. 1012
  25. 350
  26. 1199
  27. 303
  28. 811
  29. 151
  30. 937
  31. 290
  32. 155
  33. 734
  34. 854
  35. 1291
  36. 587
  37. 346
  38. 620
  39. 1036
  40. 473

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