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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 338 · 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. 1.424 + 301 =
  2. 2.576 − 179 =
  3. 3.857 − 619 =
  4. 4.653 − 291 =
  5. 5.142 + 381 =
  6. 6.897 − 782 =
  7. 7.360 + 376 =
  8. 8.491 + 434 =
  9. 9.890 − 159 =
  10. 10.590 − 132 =
  11. 11.507 − 203 =
  12. 12.957 − 709 =
  13. 13.390 + 511 =
  14. 14.488 + 243 =
  15. 15.678 + 623 =
  16. 16.658 + 361 =
  17. 17.187 + 162 =
  18. 18.845 − 211 =
  19. 19.893 − 192 =
  20. 20.948 − 793 =
  21. 21.235 + 322 =
  22. 22.605 + 353 =
  23. 23.552 − 163 =
  24. 24.818 − 683 =
  25. 25.588 + 325 =
  26. 26.678 + 313 =
  27. 27.164 + 371 =
  28. 28.627 − 477 =
  29. 29.340 + 615 =
  30. 30.783 + 484 =
  31. 31.516 − 221 =
  32. 32.427 − 294 =
  33. 33.344 + 427 =
  34. 34.780 + 193 =
  35. 35.600 − 129 =
  36. 36.426 − 142 =
  37. 37.366 + 578 =
  38. 38.754 − 403 =
  39. 39.720 − 511 =
  40. 40.662 − 345 =

Answer key

  1. 725
  2. 397
  3. 238
  4. 362
  5. 523
  6. 115
  7. 736
  8. 925
  9. 731
  10. 458
  11. 304
  12. 248
  13. 901
  14. 731
  15. 1301
  16. 1019
  17. 349
  18. 634
  19. 701
  20. 155
  21. 557
  22. 958
  23. 389
  24. 135
  25. 913
  26. 991
  27. 535
  28. 150
  29. 955
  30. 1267
  31. 295
  32. 133
  33. 771
  34. 973
  35. 471
  36. 284
  37. 944
  38. 351
  39. 209
  40. 317

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