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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 296 · 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. 1.843 − 537 =
  2. 2.628 − 245 =
  3. 3.313 + 362 =
  4. 4.131 + 441 =
  5. 5.235 + 184 =
  6. 6.628 + 558 =
  7. 7.580 + 549 =
  8. 8.159 + 337 =
  9. 9.917 − 814 =
  10. 10.654 + 373 =
  11. 11.371 + 184 =
  12. 12.381 + 429 =
  13. 13.531 − 255 =
  14. 14.778 − 504 =
  15. 15.339 + 327 =
  16. 16.575 + 241 =
  17. 17.734 + 376 =
  18. 18.903 − 695 =
  19. 19.520 − 343 =
  20. 20.588 + 214 =
  21. 21.648 + 186 =
  22. 22.263 + 183 =
  23. 23.953 − 851 =
  24. 24.616 − 462 =
  25. 25.677 + 366 =
  26. 26.447 + 614 =
  27. 27.500 + 447 =
  28. 28.403 + 577 =
  29. 29.941 − 251 =
  30. 30.471 − 328 =
  31. 31.732 − 536 =
  32. 32.142 + 634 =
  33. 33.599 + 269 =
  34. 34.305 + 568 =
  35. 35.429 + 195 =
  36. 36.422 − 251 =
  37. 37.563 − 336 =
  38. 38.849 − 279 =
  39. 39.551 + 523 =
  40. 40.259 + 394 =

Answer key

  1. 306
  2. 383
  3. 675
  4. 572
  5. 419
  6. 1186
  7. 1129
  8. 496
  9. 103
  10. 1027
  11. 555
  12. 810
  13. 276
  14. 274
  15. 666
  16. 816
  17. 1110
  18. 208
  19. 177
  20. 802
  21. 834
  22. 446
  23. 102
  24. 154
  25. 1043
  26. 1061
  27. 947
  28. 980
  29. 690
  30. 143
  31. 196
  32. 776
  33. 868
  34. 873
  35. 624
  36. 171
  37. 227
  38. 570
  39. 1074
  40. 653

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