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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 119 · 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. 1.575 − 171 =
  2. 2.737 − 577 =
  3. 3.666 − 233 =
  4. 4.649 − 318 =
  5. 5.542 + 514 =
  6. 6.616 − 262 =
  7. 7.668 − 411 =
  8. 8.314 + 497 =
  9. 9.435 − 169 =
  10. 10.624 + 164 =
  11. 11.177 + 566 =
  12. 12.805 − 398 =
  13. 13.580 − 191 =
  14. 14.980 − 472 =
  15. 15.685 + 395 =
  16. 16.518 − 319 =
  17. 17.573 − 255 =
  18. 18.708 + 183 =
  19. 19.852 − 637 =
  20. 20.873 − 555 =
  21. 21.698 + 586 =
  22. 22.527 + 448 =
  23. 23.607 + 422 =
  24. 24.681 + 638 =
  25. 25.380 + 469 =
  26. 26.917 − 423 =
  27. 27.580 + 172 =
  28. 28.883 − 373 =
  29. 29.808 − 117 =
  30. 30.302 + 278 =
  31. 31.949 − 661 =
  32. 32.629 + 301 =
  33. 33.214 + 518 =
  34. 34.394 + 599 =
  35. 35.670 + 172 =
  36. 36.545 − 147 =
  37. 37.276 + 119 =
  38. 38.127 + 267 =
  39. 39.425 − 286 =
  40. 40.777 + 345 =

Answer key

  1. 404
  2. 160
  3. 433
  4. 331
  5. 1056
  6. 354
  7. 257
  8. 811
  9. 266
  10. 788
  11. 743
  12. 407
  13. 389
  14. 508
  15. 1080
  16. 199
  17. 318
  18. 891
  19. 215
  20. 318
  21. 1284
  22. 975
  23. 1029
  24. 1319
  25. 849
  26. 494
  27. 752
  28. 510
  29. 691
  30. 580
  31. 288
  32. 930
  33. 732
  34. 993
  35. 842
  36. 398
  37. 395
  38. 394
  39. 139
  40. 1122

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