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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 73 · 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. 1.437 − 199 =
  2. 2.776 + 475 =
  3. 3.748 − 485 =
  4. 4.304 + 643 =
  5. 5.814 − 661 =
  6. 6.878 − 313 =
  7. 7.320 + 284 =
  8. 8.976 − 296 =
  9. 9.791 − 461 =
  10. 10.562 + 552 =
  11. 11.714 − 119 =
  12. 12.586 + 229 =
  13. 13.609 + 163 =
  14. 14.906 − 728 =
  15. 15.500 + 526 =
  16. 16.878 − 338 =
  17. 17.779 + 198 =
  18. 18.731 − 541 =
  19. 19.805 − 175 =
  20. 20.483 − 376 =
  21. 21.806 − 171 =
  22. 22.867 − 311 =
  23. 23.243 + 271 =
  24. 24.476 − 115 =
  25. 25.276 + 227 =
  26. 26.527 + 444 =
  27. 27.325 + 325 =
  28. 28.124 + 358 =
  29. 29.391 + 272 =
  30. 30.542 − 371 =
  31. 31.332 + 377 =
  32. 32.727 − 291 =
  33. 33.708 − 302 =
  34. 34.745 − 181 =
  35. 35.439 − 131 =
  36. 36.483 + 268 =
  37. 37.551 + 486 =
  38. 38.475 − 122 =
  39. 39.357 + 675 =
  40. 40.523 + 321 =

Answer key

  1. 238
  2. 1251
  3. 263
  4. 947
  5. 153
  6. 565
  7. 604
  8. 680
  9. 330
  10. 1114
  11. 595
  12. 815
  13. 772
  14. 178
  15. 1026
  16. 540
  17. 977
  18. 190
  19. 630
  20. 107
  21. 635
  22. 556
  23. 514
  24. 361
  25. 503
  26. 971
  27. 650
  28. 482
  29. 663
  30. 171
  31. 709
  32. 436
  33. 406
  34. 564
  35. 308
  36. 751
  37. 1037
  38. 353
  39. 1032
  40. 844

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