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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 977 · 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. 1.619 + 187 =
  2. 2.439 + 445 =
  3. 3.728 − 449 =
  4. 4.167 + 122 =
  5. 5.506 − 118 =
  6. 6.861 − 748 =
  7. 7.590 − 484 =
  8. 8.350 + 464 =
  9. 9.395 + 601 =
  10. 10.678 − 277 =
  11. 11.525 + 611 =
  12. 12.420 + 631 =
  13. 13.738 − 175 =
  14. 14.863 − 437 =
  15. 15.951 − 437 =
  16. 16.505 + 387 =
  17. 17.833 − 711 =
  18. 18.560 − 198 =
  19. 19.518 + 281 =
  20. 20.200 + 676 =
  21. 21.374 + 198 =
  22. 22.574 − 389 =
  23. 23.349 + 599 =
  24. 24.240 + 519 =
  25. 25.632 + 424 =
  26. 26.945 − 384 =
  27. 27.491 − 269 =
  28. 28.682 + 425 =
  29. 29.405 + 658 =
  30. 30.941 − 156 =
  31. 31.406 + 438 =
  32. 32.407 + 681 =
  33. 33.709 − 376 =
  34. 34.681 − 487 =
  35. 35.436 − 139 =
  36. 36.958 − 552 =
  37. 37.738 + 249 =
  38. 38.633 + 488 =
  39. 39.436 − 162 =
  40. 40.485 − 205 =

Answer key

  1. 806
  2. 884
  3. 279
  4. 289
  5. 388
  6. 113
  7. 106
  8. 814
  9. 996
  10. 401
  11. 1136
  12. 1051
  13. 563
  14. 426
  15. 514
  16. 892
  17. 122
  18. 362
  19. 799
  20. 876
  21. 572
  22. 185
  23. 948
  24. 759
  25. 1056
  26. 561
  27. 222
  28. 1107
  29. 1063
  30. 785
  31. 844
  32. 1088
  33. 333
  34. 194
  35. 297
  36. 406
  37. 987
  38. 1121
  39. 274
  40. 280

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