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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 154 · 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. 1.965 − 752 =
  2. 2.670 + 144 =
  3. 3.853 − 509 =
  4. 4.736 − 471 =
  5. 5.826 − 195 =
  6. 6.584 − 168 =
  7. 7.213 + 337 =
  8. 8.668 − 338 =
  9. 9.694 + 397 =
  10. 10.786 − 341 =
  11. 11.444 + 151 =
  12. 12.169 + 313 =
  13. 13.555 + 454 =
  14. 14.504 − 388 =
  15. 15.163 + 209 =
  16. 16.336 + 356 =
  17. 17.694 − 396 =
  18. 18.166 + 395 =
  19. 19.807 − 524 =
  20. 20.160 + 172 =
  21. 21.486 + 536 =
  22. 22.510 + 569 =
  23. 23.238 + 449 =
  24. 24.593 + 207 =
  25. 25.526 − 234 =
  26. 26.416 − 153 =
  27. 27.439 − 114 =
  28. 28.896 − 641 =
  29. 29.833 − 204 =
  30. 30.891 − 607 =
  31. 31.552 + 635 =
  32. 32.531 − 301 =
  33. 33.376 + 367 =
  34. 34.547 + 501 =
  35. 35.412 − 158 =
  36. 36.617 − 166 =
  37. 37.567 − 371 =
  38. 38.455 + 411 =
  39. 39.903 − 439 =
  40. 40.273 + 351 =

Answer key

  1. 213
  2. 814
  3. 344
  4. 265
  5. 631
  6. 416
  7. 550
  8. 330
  9. 1091
  10. 445
  11. 595
  12. 482
  13. 1009
  14. 116
  15. 372
  16. 692
  17. 298
  18. 561
  19. 283
  20. 332
  21. 1022
  22. 1079
  23. 687
  24. 800
  25. 292
  26. 263
  27. 325
  28. 255
  29. 629
  30. 284
  31. 1187
  32. 230
  33. 743
  34. 1048
  35. 254
  36. 451
  37. 196
  38. 866
  39. 464
  40. 624

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