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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 276 · 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. 1.176 + 631 =
  2. 2.422 − 311 =
  3. 3.692 − 118 =
  4. 4.690 − 581 =
  5. 5.776 + 232 =
  6. 6.633 − 407 =
  7. 7.198 + 496 =
  8. 8.696 + 191 =
  9. 9.502 + 114 =
  10. 10.753 − 168 =
  11. 11.426 − 141 =
  12. 12.552 − 423 =
  13. 13.611 − 151 =
  14. 14.624 − 376 =
  15. 15.663 + 584 =
  16. 16.633 − 457 =
  17. 17.552 + 404 =
  18. 18.608 − 389 =
  19. 19.465 − 127 =
  20. 20.155 + 192 =
  21. 21.524 − 285 =
  22. 22.373 + 216 =
  23. 23.813 − 513 =
  24. 24.852 − 742 =
  25. 25.253 + 569 =
  26. 26.644 − 423 =
  27. 27.381 + 685 =
  28. 28.626 + 618 =
  29. 29.516 − 391 =
  30. 30.596 + 165 =
  31. 31.773 − 397 =
  32. 32.570 + 291 =
  33. 33.231 + 652 =
  34. 34.652 − 235 =
  35. 35.187 + 313 =
  36. 36.504 − 336 =
  37. 37.841 − 711 =
  38. 38.581 + 617 =
  39. 39.803 − 446 =
  40. 40.258 + 423 =

Answer key

  1. 807
  2. 111
  3. 574
  4. 109
  5. 1008
  6. 226
  7. 694
  8. 887
  9. 616
  10. 585
  11. 285
  12. 129
  13. 460
  14. 248
  15. 1247
  16. 176
  17. 956
  18. 219
  19. 338
  20. 347
  21. 239
  22. 589
  23. 300
  24. 110
  25. 822
  26. 221
  27. 1066
  28. 1244
  29. 125
  30. 761
  31. 376
  32. 861
  33. 883
  34. 417
  35. 500
  36. 168
  37. 130
  38. 1198
  39. 357
  40. 681

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