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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 95 · 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. 1.640 + 211 =
  2. 2.124 + 671 =
  3. 3.917 − 686 =
  4. 4.297 + 505 =
  5. 5.290 + 301 =
  6. 6.138 + 629 =
  7. 7.569 + 622 =
  8. 8.764 + 371 =
  9. 9.262 + 171 =
  10. 10.791 − 486 =
  11. 11.500 − 305 =
  12. 12.598 − 182 =
  13. 13.661 + 144 =
  14. 14.124 + 337 =
  15. 15.729 − 141 =
  16. 16.355 + 431 =
  17. 17.258 + 213 =
  18. 18.569 − 431 =
  19. 19.337 + 336 =
  20. 20.686 − 192 =
  21. 21.739 − 347 =
  22. 22.353 + 198 =
  23. 23.200 + 428 =
  24. 24.468 + 335 =
  25. 25.257 + 291 =
  26. 26.211 + 321 =
  27. 27.352 + 609 =
  28. 28.431 + 346 =
  29. 29.931 − 278 =
  30. 30.769 + 649 =
  31. 31.664 − 414 =
  32. 32.173 + 367 =
  33. 33.370 + 283 =
  34. 34.477 + 413 =
  35. 35.586 + 206 =
  36. 36.541 − 385 =
  37. 37.628 + 361 =
  38. 38.796 − 186 =
  39. 39.555 − 401 =
  40. 40.667 + 455 =

Answer key

  1. 851
  2. 795
  3. 231
  4. 802
  5. 591
  6. 767
  7. 1191
  8. 1135
  9. 433
  10. 305
  11. 195
  12. 416
  13. 805
  14. 461
  15. 588
  16. 786
  17. 471
  18. 138
  19. 673
  20. 494
  21. 392
  22. 551
  23. 628
  24. 803
  25. 548
  26. 532
  27. 961
  28. 777
  29. 653
  30. 1418
  31. 250
  32. 540
  33. 653
  34. 890
  35. 792
  36. 156
  37. 989
  38. 610
  39. 154
  40. 1122

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