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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 714 · 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. 1.275 + 651 =
  2. 2.350 + 137 =
  3. 3.778 + 324 =
  4. 4.590 − 339 =
  5. 5.595 + 617 =
  6. 6.771 − 664 =
  7. 7.158 + 596 =
  8. 8.447 + 454 =
  9. 9.578 + 554 =
  10. 10.794 − 654 =
  11. 11.624 − 141 =
  12. 12.354 + 645 =
  13. 13.915 − 167 =
  14. 14.277 + 231 =
  15. 15.527 − 147 =
  16. 16.596 + 376 =
  17. 17.729 − 475 =
  18. 18.495 − 222 =
  19. 19.560 + 289 =
  20. 20.173 + 437 =
  21. 21.973 − 723 =
  22. 22.246 + 541 =
  23. 23.484 + 629 =
  24. 24.763 − 296 =
  25. 25.589 + 276 =
  26. 26.435 − 171 =
  27. 27.485 − 167 =
  28. 28.244 + 392 =
  29. 29.637 − 418 =
  30. 30.657 + 213 =
  31. 31.820 − 391 =
  32. 32.343 + 613 =
  33. 33.442 + 174 =
  34. 34.798 − 367 =
  35. 35.150 + 388 =
  36. 36.863 − 536 =
  37. 37.614 − 262 =
  38. 38.237 + 626 =
  39. 39.475 − 375 =
  40. 40.676 − 118 =

Answer key

  1. 926
  2. 487
  3. 1102
  4. 251
  5. 1212
  6. 107
  7. 754
  8. 901
  9. 1132
  10. 140
  11. 483
  12. 999
  13. 748
  14. 508
  15. 380
  16. 972
  17. 254
  18. 273
  19. 849
  20. 610
  21. 250
  22. 787
  23. 1113
  24. 467
  25. 865
  26. 264
  27. 318
  28. 636
  29. 219
  30. 870
  31. 429
  32. 956
  33. 616
  34. 431
  35. 538
  36. 327
  37. 352
  38. 863
  39. 100
  40. 558

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