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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 574 · 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. 1.233 + 305 =
  2. 2.173 + 299 =
  3. 3.183 + 683 =
  4. 4.706 + 465 =
  5. 5.548 − 145 =
  6. 6.775 − 307 =
  7. 7.616 + 465 =
  8. 8.679 + 138 =
  9. 9.492 − 258 =
  10. 10.666 + 591 =
  11. 11.505 + 121 =
  12. 12.629 + 454 =
  13. 13.677 + 308 =
  14. 14.316 + 579 =
  15. 15.167 + 228 =
  16. 16.670 − 133 =
  17. 17.443 + 228 =
  18. 18.718 + 506 =
  19. 19.700 + 119 =
  20. 20.208 + 188 =
  21. 21.313 + 686 =
  22. 22.877 − 448 =
  23. 23.474 − 119 =
  24. 24.746 + 231 =
  25. 25.456 + 188 =
  26. 26.955 − 185 =
  27. 27.522 + 122 =
  28. 28.913 − 683 =
  29. 29.730 − 505 =
  30. 30.788 + 679 =
  31. 31.428 + 638 =
  32. 32.928 − 612 =
  33. 33.396 + 461 =
  34. 34.972 − 141 =
  35. 35.133 + 434 =
  36. 36.484 + 675 =
  37. 37.174 + 228 =
  38. 38.924 − 799 =
  39. 39.927 − 128 =
  40. 40.508 + 113 =

Answer key

  1. 538
  2. 472
  3. 866
  4. 1171
  5. 403
  6. 468
  7. 1081
  8. 817
  9. 234
  10. 1257
  11. 626
  12. 1083
  13. 985
  14. 895
  15. 395
  16. 537
  17. 671
  18. 1224
  19. 819
  20. 396
  21. 999
  22. 429
  23. 355
  24. 977
  25. 644
  26. 770
  27. 644
  28. 230
  29. 225
  30. 1467
  31. 1066
  32. 316
  33. 857
  34. 831
  35. 567
  36. 1159
  37. 402
  38. 125
  39. 799
  40. 621

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