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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 764 · 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. 1.333 + 677 =
  2. 2.470 − 173 =
  3. 3.645 − 267 =
  4. 4.495 + 219 =
  5. 5.591 − 369 =
  6. 6.123 + 279 =
  7. 7.419 + 151 =
  8. 8.303 + 531 =
  9. 9.548 − 287 =
  10. 10.274 + 425 =
  11. 11.988 − 251 =
  12. 12.738 + 405 =
  13. 13.733 − 611 =
  14. 14.484 + 328 =
  15. 15.559 − 415 =
  16. 16.528 + 528 =
  17. 17.742 + 243 =
  18. 18.466 − 336 =
  19. 19.302 + 336 =
  20. 20.721 − 538 =
  21. 21.564 − 317 =
  22. 22.878 − 323 =
  23. 23.492 − 306 =
  24. 24.413 − 152 =
  25. 25.559 − 274 =
  26. 26.734 + 341 =
  27. 27.166 + 656 =
  28. 28.195 + 569 =
  29. 29.741 + 681 =
  30. 30.973 − 546 =
  31. 31.185 + 571 =
  32. 32.780 + 428 =
  33. 33.765 + 371 =
  34. 34.836 − 655 =
  35. 35.261 + 436 =
  36. 36.558 + 511 =
  37. 37.466 − 181 =
  38. 38.429 − 277 =
  39. 39.333 + 151 =
  40. 40.864 − 349 =

Answer key

  1. 1010
  2. 297
  3. 378
  4. 714
  5. 222
  6. 402
  7. 570
  8. 834
  9. 261
  10. 699
  11. 737
  12. 1143
  13. 122
  14. 812
  15. 144
  16. 1056
  17. 985
  18. 130
  19. 638
  20. 183
  21. 247
  22. 555
  23. 186
  24. 261
  25. 285
  26. 1075
  27. 822
  28. 764
  29. 1422
  30. 427
  31. 756
  32. 1208
  33. 1136
  34. 181
  35. 697
  36. 1069
  37. 285
  38. 152
  39. 484
  40. 515

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