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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 736 · 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. 1.670 − 492 =
  2. 2.556 + 125 =
  3. 3.477 − 289 =
  4. 4.231 + 286 =
  5. 5.460 + 426 =
  6. 6.620 − 258 =
  7. 7.527 + 491 =
  8. 8.216 + 602 =
  9. 9.698 − 283 =
  10. 10.653 + 488 =
  11. 11.632 − 121 =
  12. 12.446 + 234 =
  13. 13.300 + 191 =
  14. 14.149 + 421 =
  15. 15.595 + 153 =
  16. 16.442 − 202 =
  17. 17.174 + 253 =
  18. 18.610 − 287 =
  19. 19.575 − 205 =
  20. 20.454 − 313 =
  21. 21.542 − 241 =
  22. 22.568 − 386 =
  23. 23.741 + 238 =
  24. 24.143 + 421 =
  25. 25.913 − 408 =
  26. 26.553 − 122 =
  27. 27.247 + 314 =
  28. 28.346 + 229 =
  29. 29.752 + 642 =
  30. 30.764 − 191 =
  31. 31.741 − 312 =
  32. 32.570 + 497 =
  33. 33.628 + 192 =
  34. 34.214 + 565 =
  35. 35.582 + 327 =
  36. 36.587 − 457 =
  37. 37.813 − 299 =
  38. 38.135 + 642 =
  39. 39.758 − 558 =
  40. 40.347 + 204 =

Answer key

  1. 178
  2. 681
  3. 188
  4. 517
  5. 886
  6. 362
  7. 1018
  8. 818
  9. 415
  10. 1141
  11. 511
  12. 680
  13. 491
  14. 570
  15. 748
  16. 240
  17. 427
  18. 323
  19. 370
  20. 141
  21. 301
  22. 182
  23. 979
  24. 564
  25. 505
  26. 431
  27. 561
  28. 575
  29. 1394
  30. 573
  31. 429
  32. 1067
  33. 820
  34. 779
  35. 909
  36. 130
  37. 514
  38. 777
  39. 200
  40. 551

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