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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 349 · 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. 1.627 + 211 =
  2. 2.619 + 528 =
  3. 3.941 − 357 =
  4. 4.886 − 258 =
  5. 5.394 + 194 =
  6. 6.884 − 531 =
  7. 7.930 − 166 =
  8. 8.976 − 236 =
  9. 9.744 − 204 =
  10. 10.669 − 194 =
  11. 11.279 + 539 =
  12. 12.803 − 222 =
  13. 13.506 + 581 =
  14. 14.558 − 399 =
  15. 15.522 − 149 =
  16. 16.503 − 225 =
  17. 17.692 + 237 =
  18. 18.193 + 263 =
  19. 19.624 − 212 =
  20. 20.287 + 677 =
  21. 21.929 − 325 =
  22. 22.711 − 497 =
  23. 23.777 − 555 =
  24. 24.586 + 276 =
  25. 25.424 + 575 =
  26. 26.439 + 389 =
  27. 27.157 + 648 =
  28. 28.600 + 531 =
  29. 29.528 + 141 =
  30. 30.166 + 443 =
  31. 31.552 + 187 =
  32. 32.975 − 267 =
  33. 33.649 − 385 =
  34. 34.422 + 341 =
  35. 35.445 − 275 =
  36. 36.312 + 545 =
  37. 37.883 − 154 =
  38. 38.165 + 611 =
  39. 39.738 + 469 =
  40. 40.970 − 846 =

Answer key

  1. 838
  2. 1147
  3. 584
  4. 628
  5. 588
  6. 353
  7. 764
  8. 740
  9. 540
  10. 475
  11. 818
  12. 581
  13. 1087
  14. 159
  15. 373
  16. 278
  17. 929
  18. 456
  19. 412
  20. 964
  21. 604
  22. 214
  23. 222
  24. 862
  25. 999
  26. 828
  27. 805
  28. 1131
  29. 669
  30. 609
  31. 739
  32. 708
  33. 264
  34. 763
  35. 170
  36. 857
  37. 729
  38. 776
  39. 1207
  40. 124

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