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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 816 · 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. 1.824 − 278 =
  2. 2.571 + 215 =
  3. 3.453 − 246 =
  4. 4.815 − 293 =
  5. 5.340 + 356 =
  6. 6.389 + 116 =
  7. 7.425 + 284 =
  8. 8.559 − 277 =
  9. 9.175 + 646 =
  10. 10.831 − 708 =
  11. 11.463 − 143 =
  12. 12.677 − 177 =
  13. 13.653 + 368 =
  14. 14.580 − 335 =
  15. 15.636 + 241 =
  16. 16.766 + 378 =
  17. 17.268 + 528 =
  18. 18.602 − 181 =
  19. 19.588 − 293 =
  20. 20.704 + 648 =
  21. 21.127 + 278 =
  22. 22.417 − 259 =
  23. 23.514 − 216 =
  24. 24.984 − 439 =
  25. 25.722 − 601 =
  26. 26.635 + 477 =
  27. 27.551 − 321 =
  28. 28.753 − 171 =
  29. 29.408 + 261 =
  30. 30.949 − 708 =
  31. 31.377 + 133 =
  32. 32.745 − 438 =
  33. 33.512 − 352 =
  34. 34.532 + 208 =
  35. 35.742 + 125 =
  36. 36.537 − 191 =
  37. 37.597 + 544 =
  38. 38.589 + 455 =
  39. 39.867 − 218 =
  40. 40.647 − 366 =

Answer key

  1. 546
  2. 786
  3. 207
  4. 522
  5. 696
  6. 505
  7. 709
  8. 282
  9. 821
  10. 123
  11. 320
  12. 500
  13. 1021
  14. 245
  15. 877
  16. 1144
  17. 796
  18. 421
  19. 295
  20. 1352
  21. 405
  22. 158
  23. 298
  24. 545
  25. 121
  26. 1112
  27. 230
  28. 582
  29. 669
  30. 241
  31. 510
  32. 307
  33. 160
  34. 740
  35. 867
  36. 346
  37. 1141
  38. 1044
  39. 649
  40. 281

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