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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 835 · 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. 1.687 − 314 =
  2. 2.808 − 232 =
  3. 3.487 − 251 =
  4. 4.657 + 163 =
  5. 5.233 + 528 =
  6. 6.196 + 141 =
  7. 7.740 − 344 =
  8. 8.655 + 146 =
  9. 9.958 − 541 =
  10. 10.792 − 667 =
  11. 11.566 − 293 =
  12. 12.579 − 217 =
  13. 13.939 − 347 =
  14. 14.586 − 338 =
  15. 15.438 − 206 =
  16. 16.324 + 506 =
  17. 17.143 + 368 =
  18. 18.557 − 411 =
  19. 19.511 + 259 =
  20. 20.221 + 594 =
  21. 21.134 + 281 =
  22. 22.579 − 184 =
  23. 23.585 − 347 =
  24. 24.582 − 317 =
  25. 25.622 − 488 =
  26. 26.292 + 289 =
  27. 27.284 + 392 =
  28. 28.732 − 338 =
  29. 29.276 + 223 =
  30. 30.145 + 617 =
  31. 31.565 − 408 =
  32. 32.555 − 209 =
  33. 33.651 − 391 =
  34. 34.741 − 243 =
  35. 35.154 + 555 =
  36. 36.454 − 312 =
  37. 37.713 + 435 =
  38. 38.688 − 261 =
  39. 39.263 + 605 =
  40. 40.388 + 198 =

Answer key

  1. 373
  2. 576
  3. 236
  4. 820
  5. 761
  6. 337
  7. 396
  8. 801
  9. 417
  10. 125
  11. 273
  12. 362
  13. 592
  14. 248
  15. 232
  16. 830
  17. 511
  18. 146
  19. 770
  20. 815
  21. 415
  22. 395
  23. 238
  24. 265
  25. 134
  26. 581
  27. 676
  28. 394
  29. 499
  30. 762
  31. 157
  32. 346
  33. 260
  34. 498
  35. 709
  36. 142
  37. 1148
  38. 427
  39. 868
  40. 586

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