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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 748 · 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. 1.608 + 336 =
  2. 2.249 + 681 =
  3. 3.230 + 392 =
  4. 4.370 + 221 =
  5. 5.631 + 531 =
  6. 6.612 − 322 =
  7. 7.561 − 344 =
  8. 8.660 + 273 =
  9. 9.763 + 293 =
  10. 10.227 + 444 =
  11. 11.584 + 462 =
  12. 12.271 + 605 =
  13. 13.236 + 187 =
  14. 14.243 + 206 =
  15. 15.202 + 262 =
  16. 16.441 + 459 =
  17. 17.598 + 652 =
  18. 18.303 + 579 =
  19. 19.430 − 168 =
  20. 20.818 − 145 =
  21. 21.443 − 291 =
  22. 22.429 + 248 =
  23. 23.547 + 171 =
  24. 24.457 + 421 =
  25. 25.452 − 179 =
  26. 26.559 + 171 =
  27. 27.224 + 431 =
  28. 28.598 − 482 =
  29. 29.836 − 696 =
  30. 30.175 + 186 =
  31. 31.492 − 353 =
  32. 32.692 − 209 =
  33. 33.940 − 839 =
  34. 34.188 + 431 =
  35. 35.264 + 382 =
  36. 36.163 + 635 =
  37. 37.934 − 441 =
  38. 38.709 − 356 =
  39. 39.282 + 503 =
  40. 40.712 + 248 =

Answer key

  1. 944
  2. 930
  3. 622
  4. 591
  5. 1162
  6. 290
  7. 217
  8. 933
  9. 1056
  10. 671
  11. 1046
  12. 876
  13. 423
  14. 449
  15. 464
  16. 900
  17. 1250
  18. 882
  19. 262
  20. 673
  21. 152
  22. 677
  23. 718
  24. 878
  25. 273
  26. 730
  27. 655
  28. 116
  29. 140
  30. 361
  31. 139
  32. 483
  33. 101
  34. 619
  35. 646
  36. 798
  37. 493
  38. 353
  39. 785
  40. 960

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