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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 212 · 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. 1.490 − 158 =
  2. 2.379 + 349 =
  3. 3.305 + 374 =
  4. 4.372 + 406 =
  5. 5.436 − 168 =
  6. 6.609 + 305 =
  7. 7.490 + 683 =
  8. 8.640 + 514 =
  9. 9.741 − 191 =
  10. 10.458 − 208 =
  11. 11.202 + 254 =
  12. 12.318 + 393 =
  13. 13.678 + 564 =
  14. 14.551 − 351 =
  15. 15.908 − 525 =
  16. 16.681 + 545 =
  17. 17.624 − 181 =
  18. 18.234 + 131 =
  19. 19.468 − 231 =
  20. 20.702 − 594 =
  21. 21.785 + 151 =
  22. 22.918 − 545 =
  23. 23.600 + 205 =
  24. 24.738 − 125 =
  25. 25.305 + 596 =
  26. 26.498 + 373 =
  27. 27.484 + 309 =
  28. 28.263 + 594 =
  29. 29.893 − 195 =
  30. 30.444 − 133 =
  31. 31.621 − 466 =
  32. 32.734 − 285 =
  33. 33.306 + 673 =
  34. 34.336 + 546 =
  35. 35.187 + 236 =
  36. 36.891 − 471 =
  37. 37.525 + 113 =
  38. 38.670 + 543 =
  39. 39.574 − 463 =
  40. 40.460 − 169 =

Answer key

  1. 332
  2. 728
  3. 679
  4. 778
  5. 268
  6. 914
  7. 1173
  8. 1154
  9. 550
  10. 250
  11. 456
  12. 711
  13. 1242
  14. 200
  15. 383
  16. 1226
  17. 443
  18. 365
  19. 237
  20. 108
  21. 936
  22. 373
  23. 805
  24. 613
  25. 901
  26. 871
  27. 793
  28. 857
  29. 698
  30. 311
  31. 155
  32. 449
  33. 979
  34. 882
  35. 423
  36. 420
  37. 638
  38. 1213
  39. 111
  40. 291

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