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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 237 · 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. 1.656 + 157 =
  2. 2.969 − 681 =
  3. 3.127 + 149 =
  4. 4.535 − 174 =
  5. 5.312 + 483 =
  6. 6.732 + 186 =
  7. 7.413 + 386 =
  8. 8.695 + 168 =
  9. 9.963 − 232 =
  10. 10.687 + 141 =
  11. 11.646 − 333 =
  12. 12.364 + 267 =
  13. 13.391 + 273 =
  14. 14.895 − 517 =
  15. 15.591 − 476 =
  16. 16.554 − 355 =
  17. 17.219 + 614 =
  18. 18.234 + 484 =
  19. 19.505 + 182 =
  20. 20.728 − 267 =
  21. 21.801 − 211 =
  22. 22.729 − 497 =
  23. 23.419 − 123 =
  24. 24.593 + 191 =
  25. 25.357 + 409 =
  26. 26.617 + 321 =
  27. 27.743 + 327 =
  28. 28.273 + 439 =
  29. 29.864 − 462 =
  30. 30.405 + 229 =
  31. 31.671 − 207 =
  32. 32.177 + 328 =
  33. 33.566 − 115 =
  34. 34.452 − 221 =
  35. 35.345 + 671 =
  36. 36.581 + 404 =
  37. 37.544 + 318 =
  38. 38.799 − 281 =
  39. 39.312 + 428 =
  40. 40.327 + 216 =

Answer key

  1. 813
  2. 288
  3. 276
  4. 361
  5. 795
  6. 918
  7. 799
  8. 863
  9. 731
  10. 828
  11. 313
  12. 631
  13. 664
  14. 378
  15. 115
  16. 199
  17. 833
  18. 718
  19. 687
  20. 461
  21. 590
  22. 232
  23. 296
  24. 784
  25. 766
  26. 938
  27. 1070
  28. 712
  29. 402
  30. 634
  31. 464
  32. 505
  33. 451
  34. 231
  35. 1016
  36. 985
  37. 862
  38. 518
  39. 740
  40. 543

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