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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 643 · 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. 1.823 − 568 =
  2. 2.681 − 555 =
  3. 3.960 − 197 =
  4. 4.341 + 135 =
  5. 5.171 + 159 =
  6. 6.181 + 427 =
  7. 7.188 + 298 =
  8. 8.538 + 179 =
  9. 9.528 + 447 =
  10. 10.580 + 611 =
  11. 11.583 − 481 =
  12. 12.678 − 481 =
  13. 13.498 + 681 =
  14. 14.976 − 661 =
  15. 15.469 + 408 =
  16. 16.566 − 201 =
  17. 17.208 + 523 =
  18. 18.476 − 239 =
  19. 19.693 − 452 =
  20. 20.535 + 421 =
  21. 21.197 + 277 =
  22. 22.907 − 638 =
  23. 23.563 − 409 =
  24. 24.285 + 553 =
  25. 25.427 + 651 =
  26. 26.679 − 127 =
  27. 27.177 + 658 =
  28. 28.529 − 223 =
  29. 29.552 + 356 =
  30. 30.957 − 191 =
  31. 31.686 + 555 =
  32. 32.245 + 196 =
  33. 33.716 − 396 =
  34. 34.708 + 529 =
  35. 35.427 − 131 =
  36. 36.366 + 321 =
  37. 37.520 − 201 =
  38. 38.538 − 245 =
  39. 39.738 − 394 =
  40. 40.539 + 437 =

Answer key

  1. 255
  2. 126
  3. 763
  4. 476
  5. 330
  6. 608
  7. 486
  8. 717
  9. 975
  10. 1191
  11. 102
  12. 197
  13. 1179
  14. 315
  15. 877
  16. 365
  17. 731
  18. 237
  19. 241
  20. 956
  21. 474
  22. 269
  23. 154
  24. 838
  25. 1078
  26. 552
  27. 835
  28. 306
  29. 908
  30. 766
  31. 1241
  32. 441
  33. 320
  34. 1237
  35. 296
  36. 687
  37. 319
  38. 293
  39. 344
  40. 976

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