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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 581 · 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. 1.857 − 271 =
  2. 2.446 + 215 =
  3. 3.606 + 128 =
  4. 4.594 + 458 =
  5. 5.545 − 408 =
  6. 6.492 − 221 =
  7. 7.600 + 559 =
  8. 8.271 + 655 =
  9. 9.763 + 276 =
  10. 10.956 − 633 =
  11. 11.607 + 161 =
  12. 12.808 − 628 =
  13. 13.698 − 144 =
  14. 14.568 − 149 =
  15. 15.529 + 504 =
  16. 16.385 + 422 =
  17. 17.984 − 818 =
  18. 18.759 − 561 =
  19. 19.608 + 661 =
  20. 20.520 + 203 =
  21. 21.509 + 658 =
  22. 22.555 + 181 =
  23. 23.440 − 119 =
  24. 24.290 + 174 =
  25. 25.600 − 418 =
  26. 26.427 + 323 =
  27. 27.902 − 535 =
  28. 28.208 + 317 =
  29. 29.458 − 127 =
  30. 30.578 + 595 =
  31. 31.430 − 174 =
  32. 32.477 − 299 =
  33. 33.168 + 295 =
  34. 34.975 − 311 =
  35. 35.508 − 399 =
  36. 36.132 + 681 =
  37. 37.679 − 376 =
  38. 38.839 − 558 =
  39. 39.346 + 287 =
  40. 40.493 + 266 =

Answer key

  1. 586
  2. 661
  3. 734
  4. 1052
  5. 137
  6. 271
  7. 1159
  8. 926
  9. 1039
  10. 323
  11. 768
  12. 180
  13. 554
  14. 419
  15. 1033
  16. 807
  17. 166
  18. 198
  19. 1269
  20. 723
  21. 1167
  22. 736
  23. 321
  24. 464
  25. 182
  26. 750
  27. 367
  28. 525
  29. 331
  30. 1173
  31. 256
  32. 178
  33. 463
  34. 664
  35. 109
  36. 813
  37. 303
  38. 281
  39. 633
  40. 759

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