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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 579 · 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. 1.815 − 543 =
  2. 2.140 + 285 =
  3. 3.619 − 185 =
  4. 4.694 − 364 =
  5. 5.810 − 187 =
  6. 6.851 − 121 =
  7. 7.600 − 396 =
  8. 8.615 + 232 =
  9. 9.761 + 424 =
  10. 10.855 − 139 =
  11. 11.750 + 531 =
  12. 12.865 − 134 =
  13. 13.674 − 503 =
  14. 14.658 − 512 =
  15. 15.158 + 305 =
  16. 16.736 − 403 =
  17. 17.738 + 538 =
  18. 18.595 + 587 =
  19. 19.370 + 275 =
  20. 20.862 − 296 =
  21. 21.477 + 181 =
  22. 22.153 + 341 =
  23. 23.565 + 391 =
  24. 24.427 + 659 =
  25. 25.376 + 535 =
  26. 26.220 + 658 =
  27. 27.686 + 328 =
  28. 28.525 + 189 =
  29. 29.901 − 144 =
  30. 30.739 + 289 =
  31. 31.759 + 442 =
  32. 32.738 + 631 =
  33. 33.783 + 501 =
  34. 34.684 + 169 =
  35. 35.262 + 259 =
  36. 36.647 − 171 =
  37. 37.206 + 625 =
  38. 38.206 + 231 =
  39. 39.708 − 578 =
  40. 40.439 + 401 =

Answer key

  1. 272
  2. 425
  3. 434
  4. 330
  5. 623
  6. 730
  7. 204
  8. 847
  9. 1185
  10. 716
  11. 1281
  12. 731
  13. 171
  14. 146
  15. 463
  16. 333
  17. 1276
  18. 1182
  19. 645
  20. 566
  21. 658
  22. 494
  23. 956
  24. 1086
  25. 911
  26. 878
  27. 1014
  28. 714
  29. 757
  30. 1028
  31. 1201
  32. 1369
  33. 1284
  34. 853
  35. 521
  36. 476
  37. 831
  38. 437
  39. 130
  40. 840

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