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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 799 · 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. 1.830 − 664 =
  2. 2.634 + 148 =
  3. 3.807 − 232 =
  4. 4.873 − 436 =
  5. 5.585 + 641 =
  6. 6.587 − 156 =
  7. 7.247 + 532 =
  8. 8.545 + 681 =
  9. 9.769 + 673 =
  10. 10.873 − 291 =
  11. 11.884 − 176 =
  12. 12.548 + 338 =
  13. 13.472 + 528 =
  14. 14.782 − 131 =
  15. 15.635 − 313 =
  16. 16.880 − 211 =
  17. 17.447 + 597 =
  18. 18.442 − 263 =
  19. 19.901 − 395 =
  20. 20.265 + 344 =
  21. 21.208 + 636 =
  22. 22.550 − 124 =
  23. 23.430 + 384 =
  24. 24.542 − 152 =
  25. 25.784 − 389 =
  26. 26.475 + 165 =
  27. 27.791 − 222 =
  28. 28.491 − 295 =
  29. 29.259 + 595 =
  30. 30.696 + 543 =
  31. 31.964 − 215 =
  32. 32.734 + 231 =
  33. 33.636 + 608 =
  34. 34.750 + 114 =
  35. 35.882 − 704 =
  36. 36.919 − 188 =
  37. 37.591 + 586 =
  38. 38.129 + 362 =
  39. 39.632 + 196 =
  40. 40.444 + 676 =

Answer key

  1. 166
  2. 782
  3. 575
  4. 437
  5. 1226
  6. 431
  7. 779
  8. 1226
  9. 1442
  10. 582
  11. 708
  12. 886
  13. 1000
  14. 651
  15. 322
  16. 669
  17. 1044
  18. 179
  19. 506
  20. 609
  21. 844
  22. 426
  23. 814
  24. 390
  25. 395
  26. 640
  27. 569
  28. 196
  29. 854
  30. 1239
  31. 749
  32. 965
  33. 1244
  34. 864
  35. 178
  36. 731
  37. 1177
  38. 491
  39. 828
  40. 1120

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