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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 812 · 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. 1.718 + 206 =
  2. 2.269 + 369 =
  3. 3.813 − 251 =
  4. 4.302 + 648 =
  5. 5.314 + 361 =
  6. 6.751 − 221 =
  7. 7.553 + 339 =
  8. 8.623 − 136 =
  9. 9.593 − 187 =
  10. 10.554 + 674 =
  11. 11.430 − 175 =
  12. 12.698 + 252 =
  13. 13.451 − 283 =
  14. 14.936 − 201 =
  15. 15.186 + 571 =
  16. 16.593 − 232 =
  17. 17.560 − 246 =
  18. 18.626 + 582 =
  19. 19.853 − 283 =
  20. 20.625 + 384 =
  21. 21.809 − 417 =
  22. 22.407 + 179 =
  23. 23.443 − 191 =
  24. 24.287 + 578 =
  25. 25.606 − 485 =
  26. 26.739 − 602 =
  27. 27.165 + 509 =
  28. 28.477 − 174 =
  29. 29.250 + 354 =
  30. 30.448 − 202 =
  31. 31.472 − 285 =
  32. 32.298 + 353 =
  33. 33.320 + 183 =
  34. 34.540 − 221 =
  35. 35.384 + 135 =
  36. 36.951 − 403 =
  37. 37.430 − 207 =
  38. 38.304 + 382 =
  39. 39.211 + 151 =
  40. 40.940 − 811 =

Answer key

  1. 924
  2. 638
  3. 562
  4. 950
  5. 675
  6. 530
  7. 892
  8. 487
  9. 406
  10. 1228
  11. 255
  12. 950
  13. 168
  14. 735
  15. 757
  16. 361
  17. 314
  18. 1208
  19. 570
  20. 1009
  21. 392
  22. 586
  23. 252
  24. 865
  25. 121
  26. 137
  27. 674
  28. 303
  29. 604
  30. 246
  31. 187
  32. 651
  33. 503
  34. 319
  35. 519
  36. 548
  37. 223
  38. 686
  39. 362
  40. 129

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