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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 667 · 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. 1.281 + 259 =
  2. 2.476 + 516 =
  3. 3.548 − 447 =
  4. 4.438 − 143 =
  5. 5.544 − 273 =
  6. 6.702 − 166 =
  7. 7.541 + 351 =
  8. 8.976 − 255 =
  9. 9.484 + 502 =
  10. 10.671 − 139 =
  11. 11.976 − 868 =
  12. 12.521 − 271 =
  13. 13.741 + 227 =
  14. 14.564 − 156 =
  15. 15.656 − 299 =
  16. 16.125 + 426 =
  17. 17.351 + 355 =
  18. 18.207 + 134 =
  19. 19.885 − 117 =
  20. 20.750 − 255 =
  21. 21.447 − 148 =
  22. 22.383 + 677 =
  23. 23.330 + 561 =
  24. 24.357 + 403 =
  25. 25.975 − 488 =
  26. 26.965 − 288 =
  27. 27.779 − 159 =
  28. 28.669 − 357 =
  29. 29.427 + 153 =
  30. 30.731 + 678 =
  31. 31.746 + 673 =
  32. 32.435 − 157 =
  33. 33.641 + 165 =
  34. 34.472 − 214 =
  35. 35.936 − 371 =
  36. 36.353 + 481 =
  37. 37.275 + 364 =
  38. 38.919 − 638 =
  39. 39.455 − 247 =
  40. 40.124 + 461 =

Answer key

  1. 540
  2. 992
  3. 101
  4. 295
  5. 271
  6. 536
  7. 892
  8. 721
  9. 986
  10. 532
  11. 108
  12. 250
  13. 968
  14. 408
  15. 357
  16. 551
  17. 706
  18. 341
  19. 768
  20. 495
  21. 299
  22. 1060
  23. 891
  24. 760
  25. 487
  26. 677
  27. 620
  28. 312
  29. 580
  30. 1409
  31. 1419
  32. 278
  33. 806
  34. 258
  35. 565
  36. 834
  37. 639
  38. 281
  39. 208
  40. 585

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