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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 256 · 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. 1.918 − 513 =
  2. 2.731 + 241 =
  3. 3.698 + 145 =
  4. 4.448 − 127 =
  5. 5.838 − 553 =
  6. 6.733 + 448 =
  7. 7.460 − 323 =
  8. 8.642 − 472 =
  9. 9.946 − 582 =
  10. 10.932 − 356 =
  11. 11.666 + 341 =
  12. 12.665 − 467 =
  13. 13.976 − 175 =
  14. 14.522 + 521 =
  15. 15.418 − 313 =
  16. 16.410 + 524 =
  17. 17.522 + 176 =
  18. 18.421 + 305 =
  19. 19.966 − 774 =
  20. 20.707 + 264 =
  21. 21.835 − 531 =
  22. 22.508 − 334 =
  23. 23.768 + 146 =
  24. 24.946 − 473 =
  25. 25.230 + 434 =
  26. 26.563 + 209 =
  27. 27.861 − 191 =
  28. 28.943 − 625 =
  29. 29.648 − 444 =
  30. 30.910 − 297 =
  31. 31.888 − 201 =
  32. 32.611 + 681 =
  33. 33.416 − 238 =
  34. 34.526 − 126 =
  35. 35.527 + 374 =
  36. 36.202 + 259 =
  37. 37.473 − 313 =
  38. 38.941 − 263 =
  39. 39.744 + 591 =
  40. 40.771 − 556 =

Answer key

  1. 405
  2. 972
  3. 843
  4. 321
  5. 285
  6. 1181
  7. 137
  8. 170
  9. 364
  10. 576
  11. 1007
  12. 198
  13. 801
  14. 1043
  15. 105
  16. 934
  17. 698
  18. 726
  19. 192
  20. 971
  21. 304
  22. 174
  23. 914
  24. 473
  25. 664
  26. 772
  27. 670
  28. 318
  29. 204
  30. 613
  31. 687
  32. 1292
  33. 178
  34. 400
  35. 901
  36. 461
  37. 160
  38. 678
  39. 1335
  40. 215

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