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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 654 · 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. 1.649 + 601 =
  2. 2.601 − 487 =
  3. 3.637 − 136 =
  4. 4.159 + 131 =
  5. 5.566 − 393 =
  6. 6.488 + 233 =
  7. 7.975 − 606 =
  8. 8.624 − 522 =
  9. 9.613 − 417 =
  10. 10.989 − 432 =
  11. 11.535 − 156 =
  12. 12.872 − 204 =
  13. 13.417 − 152 =
  14. 14.447 + 484 =
  15. 15.661 − 207 =
  16. 16.164 + 402 =
  17. 17.593 − 321 =
  18. 18.826 − 359 =
  19. 19.260 + 145 =
  20. 20.163 + 552 =
  21. 21.616 + 591 =
  22. 22.520 − 212 =
  23. 23.540 + 593 =
  24. 24.785 + 342 =
  25. 25.141 + 261 =
  26. 26.174 + 531 =
  27. 27.378 + 447 =
  28. 28.711 + 649 =
  29. 29.339 + 251 =
  30. 30.752 − 569 =
  31. 31.262 + 411 =
  32. 32.564 − 147 =
  33. 33.456 − 144 =
  34. 34.522 + 328 =
  35. 35.408 + 572 =
  36. 36.458 − 261 =
  37. 37.587 − 325 =
  38. 38.565 − 196 =
  39. 39.567 − 354 =
  40. 40.534 + 645 =

Answer key

  1. 1250
  2. 114
  3. 501
  4. 290
  5. 173
  6. 721
  7. 369
  8. 102
  9. 196
  10. 557
  11. 379
  12. 668
  13. 265
  14. 931
  15. 454
  16. 566
  17. 272
  18. 467
  19. 405
  20. 715
  21. 1207
  22. 308
  23. 1133
  24. 1127
  25. 402
  26. 705
  27. 825
  28. 1360
  29. 590
  30. 183
  31. 673
  32. 417
  33. 312
  34. 850
  35. 980
  36. 197
  37. 262
  38. 369
  39. 213
  40. 1179

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