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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 698 · 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. 1.555 + 171 =
  2. 2.977 − 403 =
  3. 3.601 − 279 =
  4. 4.719 − 198 =
  5. 5.750 − 277 =
  6. 6.519 − 221 =
  7. 7.423 + 191 =
  8. 8.501 + 301 =
  9. 9.202 + 573 =
  10. 10.856 − 374 =
  11. 11.418 − 171 =
  12. 12.414 − 113 =
  13. 13.717 + 282 =
  14. 14.178 + 558 =
  15. 15.713 − 308 =
  16. 16.811 − 681 =
  17. 17.632 + 664 =
  18. 18.504 + 253 =
  19. 19.468 − 113 =
  20. 20.626 − 494 =
  21. 21.605 + 491 =
  22. 22.951 − 202 =
  23. 23.223 + 637 =
  24. 24.691 + 461 =
  25. 25.457 + 179 =
  26. 26.164 + 409 =
  27. 27.736 − 601 =
  28. 28.704 + 546 =
  29. 29.735 − 557 =
  30. 30.815 − 285 =
  31. 31.152 + 271 =
  32. 32.647 + 246 =
  33. 33.199 + 242 =
  34. 34.915 − 264 =
  35. 35.138 + 536 =
  36. 36.237 + 118 =
  37. 37.416 − 152 =
  38. 38.508 + 605 =
  39. 39.303 + 544 =
  40. 40.908 − 457 =

Answer key

  1. 726
  2. 574
  3. 322
  4. 521
  5. 473
  6. 298
  7. 614
  8. 802
  9. 775
  10. 482
  11. 247
  12. 301
  13. 999
  14. 736
  15. 405
  16. 130
  17. 1296
  18. 757
  19. 355
  20. 132
  21. 1096
  22. 749
  23. 860
  24. 1152
  25. 636
  26. 573
  27. 135
  28. 1250
  29. 178
  30. 530
  31. 423
  32. 893
  33. 441
  34. 651
  35. 674
  36. 355
  37. 264
  38. 1113
  39. 847
  40. 451

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