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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 691 · 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. 1.623 + 515 =
  2. 2.678 − 202 =
  3. 3.739 − 401 =
  4. 4.868 − 113 =
  5. 5.575 − 471 =
  6. 6.701 + 201 =
  7. 7.419 + 115 =
  8. 8.890 − 398 =
  9. 9.989 − 754 =
  10. 10.783 + 465 =
  11. 11.481 + 323 =
  12. 12.169 + 119 =
  13. 13.201 + 621 =
  14. 14.660 + 617 =
  15. 15.491 − 151 =
  16. 16.486 − 182 =
  17. 17.763 − 182 =
  18. 18.233 + 275 =
  19. 19.641 − 337 =
  20. 20.621 − 224 =
  21. 21.704 + 416 =
  22. 22.668 + 269 =
  23. 23.550 + 647 =
  24. 24.204 + 519 =
  25. 25.657 + 689 =
  26. 26.660 − 518 =
  27. 27.563 + 256 =
  28. 28.234 + 211 =
  29. 29.629 + 491 =
  30. 30.919 − 817 =
  31. 31.208 + 291 =
  32. 32.690 − 172 =
  33. 33.382 + 164 =
  34. 34.420 − 225 =
  35. 35.374 + 611 =
  36. 36.568 + 279 =
  37. 37.661 − 368 =
  38. 38.645 + 375 =
  39. 39.691 − 305 =
  40. 40.747 + 419 =

Answer key

  1. 1138
  2. 476
  3. 338
  4. 755
  5. 104
  6. 902
  7. 534
  8. 492
  9. 235
  10. 1248
  11. 804
  12. 288
  13. 822
  14. 1277
  15. 340
  16. 304
  17. 581
  18. 508
  19. 304
  20. 397
  21. 1120
  22. 937
  23. 1197
  24. 723
  25. 1346
  26. 142
  27. 819
  28. 445
  29. 1120
  30. 102
  31. 499
  32. 518
  33. 546
  34. 195
  35. 985
  36. 847
  37. 293
  38. 1020
  39. 386
  40. 1166

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