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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 272 · 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. 1.828 − 323 =
  2. 2.828 − 255 =
  3. 3.698 − 121 =
  4. 4.176 + 174 =
  5. 5.906 − 191 =
  6. 6.742 + 219 =
  7. 7.410 + 421 =
  8. 8.635 − 527 =
  9. 9.579 − 403 =
  10. 10.616 + 311 =
  11. 11.959 − 161 =
  12. 12.492 + 498 =
  13. 13.334 + 674 =
  14. 14.857 − 614 =
  15. 15.501 − 221 =
  16. 16.524 + 399 =
  17. 17.716 + 319 =
  18. 18.276 + 635 =
  19. 19.828 − 557 =
  20. 20.157 + 251 =
  21. 21.155 + 281 =
  22. 22.905 − 561 =
  23. 23.513 − 387 =
  24. 24.176 + 171 =
  25. 25.854 − 468 =
  26. 26.322 + 428 =
  27. 27.616 + 589 =
  28. 28.438 − 188 =
  29. 29.506 + 201 =
  30. 30.402 + 521 =
  31. 31.410 + 601 =
  32. 32.601 − 348 =
  33. 33.924 − 231 =
  34. 34.886 − 193 =
  35. 35.190 + 546 =
  36. 36.827 − 553 =
  37. 37.740 − 541 =
  38. 38.407 + 569 =
  39. 39.188 + 637 =
  40. 40.571 − 313 =

Answer key

  1. 505
  2. 573
  3. 577
  4. 350
  5. 715
  6. 961
  7. 831
  8. 108
  9. 176
  10. 927
  11. 798
  12. 990
  13. 1008
  14. 243
  15. 280
  16. 923
  17. 1035
  18. 911
  19. 271
  20. 408
  21. 436
  22. 344
  23. 126
  24. 347
  25. 386
  26. 750
  27. 1205
  28. 250
  29. 707
  30. 923
  31. 1011
  32. 253
  33. 693
  34. 693
  35. 736
  36. 274
  37. 199
  38. 976
  39. 825
  40. 258

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