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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 797 · 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. 1.556 + 231 =
  2. 2.454 − 291 =
  3. 3.389 + 205 =
  4. 4.684 + 198 =
  5. 5.645 − 464 =
  6. 6.583 + 119 =
  7. 7.275 + 303 =
  8. 8.766 − 665 =
  9. 9.143 + 343 =
  10. 10.536 − 308 =
  11. 11.655 + 471 =
  12. 12.639 + 354 =
  13. 13.385 + 406 =
  14. 14.325 + 396 =
  15. 15.418 − 222 =
  16. 16.234 + 165 =
  17. 17.576 + 268 =
  18. 18.697 + 272 =
  19. 19.592 + 119 =
  20. 20.446 − 318 =
  21. 21.965 − 715 =
  22. 22.503 + 201 =
  23. 23.569 − 133 =
  24. 24.581 − 311 =
  25. 25.664 + 628 =
  26. 26.633 − 499 =
  27. 27.201 + 674 =
  28. 28.441 − 224 =
  29. 29.159 + 553 =
  30. 30.438 + 431 =
  31. 31.779 − 154 =
  32. 32.678 + 225 =
  33. 33.176 + 251 =
  34. 34.844 − 338 =
  35. 35.597 − 378 =
  36. 36.139 + 356 =
  37. 37.301 + 281 =
  38. 38.162 + 174 =
  39. 39.699 + 656 =
  40. 40.711 − 358 =

Answer key

  1. 787
  2. 163
  3. 594
  4. 882
  5. 181
  6. 702
  7. 578
  8. 101
  9. 486
  10. 228
  11. 1126
  12. 993
  13. 791
  14. 721
  15. 196
  16. 399
  17. 844
  18. 969
  19. 711
  20. 128
  21. 250
  22. 704
  23. 436
  24. 270
  25. 1292
  26. 134
  27. 875
  28. 217
  29. 712
  30. 869
  31. 625
  32. 903
  33. 427
  34. 506
  35. 219
  36. 495
  37. 582
  38. 336
  39. 1355
  40. 353

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