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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 902 · 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. 1.487 − 212 =
  2. 2.362 + 131 =
  3. 3.969 − 486 =
  4. 4.916 − 501 =
  5. 5.892 − 648 =
  6. 6.165 + 214 =
  7. 7.709 − 113 =
  8. 8.625 − 243 =
  9. 9.186 + 551 =
  10. 10.572 − 227 =
  11. 11.715 + 213 =
  12. 12.894 − 746 =
  13. 13.136 + 487 =
  14. 14.167 + 193 =
  15. 15.444 − 167 =
  16. 16.427 − 158 =
  17. 17.687 − 321 =
  18. 18.777 + 142 =
  19. 19.662 − 139 =
  20. 20.624 + 254 =
  21. 21.652 + 628 =
  22. 22.522 − 236 =
  23. 23.550 − 195 =
  24. 24.319 + 411 =
  25. 25.285 + 364 =
  26. 26.729 − 241 =
  27. 27.613 + 671 =
  28. 28.639 + 364 =
  29. 29.390 + 581 =
  30. 30.414 + 392 =
  31. 31.414 + 363 =
  32. 32.215 + 222 =
  33. 33.369 + 604 =
  34. 34.147 + 163 =
  35. 35.298 + 224 =
  36. 36.270 + 432 =
  37. 37.663 + 334 =
  38. 38.603 + 627 =
  39. 39.472 − 335 =
  40. 40.942 − 484 =

Answer key

  1. 275
  2. 493
  3. 483
  4. 415
  5. 244
  6. 379
  7. 596
  8. 382
  9. 737
  10. 345
  11. 928
  12. 148
  13. 623
  14. 360
  15. 277
  16. 269
  17. 366
  18. 919
  19. 523
  20. 878
  21. 1280
  22. 286
  23. 355
  24. 730
  25. 649
  26. 488
  27. 1284
  28. 1003
  29. 971
  30. 806
  31. 777
  32. 437
  33. 973
  34. 310
  35. 522
  36. 702
  37. 997
  38. 1230
  39. 137
  40. 458

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