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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 315 · 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. 1.447 + 344 =
  2. 2.442 − 112 =
  3. 3.404 + 174 =
  4. 4.587 − 146 =
  5. 5.420 + 621 =
  6. 6.251 + 424 =
  7. 7.920 − 326 =
  8. 8.399 + 488 =
  9. 9.759 + 598 =
  10. 10.852 − 146 =
  11. 11.149 + 366 =
  12. 12.686 − 342 =
  13. 13.143 + 255 =
  14. 14.561 − 334 =
  15. 15.759 − 391 =
  16. 16.552 + 184 =
  17. 17.658 − 377 =
  18. 18.413 + 304 =
  19. 19.545 − 121 =
  20. 20.474 + 593 =
  21. 21.150 + 496 =
  22. 22.471 − 334 =
  23. 23.750 + 207 =
  24. 24.540 − 382 =
  25. 25.269 + 195 =
  26. 26.861 − 602 =
  27. 27.951 − 828 =
  28. 28.419 − 178 =
  29. 29.908 − 181 =
  30. 30.778 + 445 =
  31. 31.140 + 492 =
  32. 32.742 + 408 =
  33. 33.252 + 264 =
  34. 34.263 + 143 =
  35. 35.212 + 418 =
  36. 36.607 + 581 =
  37. 37.563 + 251 =
  38. 38.807 − 471 =
  39. 39.987 − 403 =
  40. 40.459 + 188 =

Answer key

  1. 791
  2. 330
  3. 578
  4. 441
  5. 1041
  6. 675
  7. 594
  8. 887
  9. 1357
  10. 706
  11. 515
  12. 344
  13. 398
  14. 227
  15. 368
  16. 736
  17. 281
  18. 717
  19. 424
  20. 1067
  21. 646
  22. 137
  23. 957
  24. 158
  25. 464
  26. 259
  27. 123
  28. 241
  29. 727
  30. 1223
  31. 632
  32. 1150
  33. 516
  34. 406
  35. 630
  36. 1188
  37. 814
  38. 336
  39. 584
  40. 647

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