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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 396 · 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. 1.630 − 237 =
  2. 2.536 − 368 =
  3. 3.202 + 135 =
  4. 4.780 − 374 =
  5. 5.348 + 175 =
  6. 6.617 + 358 =
  7. 7.771 − 428 =
  8. 8.228 + 317 =
  9. 9.573 + 257 =
  10. 10.211 + 591 =
  11. 11.759 − 224 =
  12. 12.478 + 526 =
  13. 13.167 + 189 =
  14. 14.555 + 381 =
  15. 15.163 + 361 =
  16. 16.205 + 483 =
  17. 17.440 + 232 =
  18. 18.494 + 245 =
  19. 19.881 − 635 =
  20. 20.955 − 686 =
  21. 21.517 − 233 =
  22. 22.447 − 243 =
  23. 23.158 + 307 =
  24. 24.348 + 584 =
  25. 25.660 − 151 =
  26. 26.322 + 153 =
  27. 27.629 + 401 =
  28. 28.803 − 665 =
  29. 29.286 + 256 =
  30. 30.447 − 177 =
  31. 31.718 + 532 =
  32. 32.918 − 711 =
  33. 33.783 + 333 =
  34. 34.832 − 171 =
  35. 35.433 + 406 =
  36. 36.308 + 333 =
  37. 37.800 − 209 =
  38. 38.772 − 411 =
  39. 39.860 − 545 =
  40. 40.673 − 134 =

Answer key

  1. 393
  2. 168
  3. 337
  4. 406
  5. 523
  6. 975
  7. 343
  8. 545
  9. 830
  10. 802
  11. 535
  12. 1004
  13. 356
  14. 936
  15. 524
  16. 688
  17. 672
  18. 739
  19. 246
  20. 269
  21. 284
  22. 204
  23. 465
  24. 932
  25. 509
  26. 475
  27. 1030
  28. 138
  29. 542
  30. 270
  31. 1250
  32. 207
  33. 1116
  34. 661
  35. 839
  36. 641
  37. 591
  38. 361
  39. 315
  40. 539

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