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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 250 · 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. 1.347 + 114 =
  2. 2.549 − 382 =
  3. 3.648 + 398 =
  4. 4.396 + 533 =
  5. 5.878 − 523 =
  6. 6.508 − 221 =
  7. 7.845 − 721 =
  8. 8.715 + 306 =
  9. 9.150 + 581 =
  10. 10.431 + 254 =
  11. 11.258 + 134 =
  12. 12.458 − 191 =
  13. 13.798 − 416 =
  14. 14.329 + 585 =
  15. 15.617 − 271 =
  16. 16.938 − 397 =
  17. 17.864 − 743 =
  18. 18.174 + 311 =
  19. 19.589 + 414 =
  20. 20.672 + 403 =
  21. 21.360 + 567 =
  22. 22.661 + 248 =
  23. 23.757 + 281 =
  24. 24.173 + 169 =
  25. 25.751 + 581 =
  26. 26.497 + 141 =
  27. 27.458 + 511 =
  28. 28.471 − 141 =
  29. 29.588 − 158 =
  30. 30.519 + 621 =
  31. 31.574 + 567 =
  32. 32.872 − 187 =
  33. 33.152 + 651 =
  34. 34.474 − 122 =
  35. 35.202 + 555 =
  36. 36.566 + 258 =
  37. 37.475 + 485 =
  38. 38.261 + 131 =
  39. 39.549 + 213 =
  40. 40.727 − 252 =

Answer key

  1. 461
  2. 167
  3. 1046
  4. 929
  5. 355
  6. 287
  7. 124
  8. 1021
  9. 731
  10. 685
  11. 392
  12. 267
  13. 382
  14. 914
  15. 346
  16. 541
  17. 121
  18. 485
  19. 1003
  20. 1075
  21. 927
  22. 909
  23. 1038
  24. 342
  25. 1332
  26. 638
  27. 969
  28. 330
  29. 430
  30. 1140
  31. 1141
  32. 685
  33. 803
  34. 352
  35. 757
  36. 824
  37. 960
  38. 392
  39. 762
  40. 475

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