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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 81 · 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. 1.725 − 262 =
  2. 2.248 + 441 =
  3. 3.425 + 165 =
  4. 4.464 − 345 =
  5. 5.228 + 261 =
  6. 6.434 + 647 =
  7. 7.233 + 506 =
  8. 8.734 + 672 =
  9. 9.908 − 781 =
  10. 10.292 + 359 =
  11. 11.504 − 116 =
  12. 12.280 + 116 =
  13. 13.719 − 421 =
  14. 14.356 + 267 =
  15. 15.958 − 477 =
  16. 16.348 + 324 =
  17. 17.631 + 188 =
  18. 18.794 − 327 =
  19. 19.245 + 572 =
  20. 20.581 + 146 =
  21. 21.690 + 249 =
  22. 22.744 − 226 =
  23. 23.723 − 211 =
  24. 24.204 + 543 =
  25. 25.841 − 145 =
  26. 26.459 + 598 =
  27. 27.437 − 216 =
  28. 28.360 + 313 =
  29. 29.823 − 621 =
  30. 30.726 − 331 =
  31. 31.761 + 205 =
  32. 32.211 + 588 =
  33. 33.677 − 167 =
  34. 34.602 + 641 =
  35. 35.569 − 221 =
  36. 36.231 + 528 =
  37. 37.166 + 292 =
  38. 38.344 + 347 =
  39. 39.714 + 245 =
  40. 40.521 − 387 =

Answer key

  1. 463
  2. 689
  3. 590
  4. 119
  5. 489
  6. 1081
  7. 739
  8. 1406
  9. 127
  10. 651
  11. 388
  12. 396
  13. 298
  14. 623
  15. 481
  16. 672
  17. 819
  18. 467
  19. 817
  20. 727
  21. 939
  22. 518
  23. 512
  24. 747
  25. 696
  26. 1057
  27. 221
  28. 673
  29. 202
  30. 395
  31. 966
  32. 799
  33. 510
  34. 1243
  35. 348
  36. 759
  37. 458
  38. 691
  39. 959
  40. 134

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