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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 867 · 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. 1.667 + 216 =
  2. 2.752 + 264 =
  3. 3.181 + 314 =
  4. 4.435 − 325 =
  5. 5.368 + 221 =
  6. 6.211 + 209 =
  7. 7.668 − 449 =
  8. 8.182 + 641 =
  9. 9.744 + 567 =
  10. 10.959 − 126 =
  11. 11.689 + 185 =
  12. 12.301 + 411 =
  13. 13.590 + 318 =
  14. 14.534 + 311 =
  15. 15.550 − 171 =
  16. 16.794 − 351 =
  17. 17.358 + 281 =
  18. 18.471 + 521 =
  19. 19.572 + 176 =
  20. 20.516 − 391 =
  21. 21.237 + 463 =
  22. 22.632 − 123 =
  23. 23.556 − 134 =
  24. 24.415 + 175 =
  25. 25.531 + 532 =
  26. 26.519 + 647 =
  27. 27.731 − 527 =
  28. 28.202 + 587 =
  29. 29.255 + 566 =
  30. 30.786 + 542 =
  31. 31.279 + 644 =
  32. 32.651 + 483 =
  33. 33.357 + 462 =
  34. 34.123 + 475 =
  35. 35.732 + 226 =
  36. 36.771 + 161 =
  37. 37.696 + 143 =
  38. 38.495 + 394 =
  39. 39.711 − 357 =
  40. 40.515 + 544 =

Answer key

  1. 883
  2. 1016
  3. 495
  4. 110
  5. 589
  6. 420
  7. 219
  8. 823
  9. 1311
  10. 833
  11. 874
  12. 712
  13. 908
  14. 845
  15. 379
  16. 443
  17. 639
  18. 992
  19. 748
  20. 125
  21. 700
  22. 509
  23. 422
  24. 590
  25. 1063
  26. 1166
  27. 204
  28. 789
  29. 821
  30. 1328
  31. 923
  32. 1134
  33. 819
  34. 598
  35. 958
  36. 932
  37. 839
  38. 889
  39. 354
  40. 1059

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