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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 911 · 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. 1.906 − 197 =
  2. 2.974 − 768 =
  3. 3.493 − 169 =
  4. 4.682 + 537 =
  5. 5.435 − 265 =
  6. 6.706 − 145 =
  7. 7.613 − 343 =
  8. 8.413 − 171 =
  9. 9.588 + 407 =
  10. 10.540 − 117 =
  11. 11.805 − 231 =
  12. 12.147 + 599 =
  13. 13.621 + 369 =
  14. 14.932 − 501 =
  15. 15.425 − 236 =
  16. 16.499 + 519 =
  17. 17.184 + 456 =
  18. 18.588 + 251 =
  19. 19.735 + 217 =
  20. 20.759 + 348 =
  21. 21.307 + 401 =
  22. 22.194 + 338 =
  23. 23.430 − 221 =
  24. 24.733 − 461 =
  25. 25.711 − 563 =
  26. 26.867 − 645 =
  27. 27.941 − 459 =
  28. 28.938 − 142 =
  29. 29.662 − 453 =
  30. 30.681 − 164 =
  31. 31.722 + 234 =
  32. 32.636 − 167 =
  33. 33.124 + 557 =
  34. 34.560 + 511 =
  35. 35.974 − 841 =
  36. 36.192 + 512 =
  37. 37.845 − 504 =
  38. 38.498 + 512 =
  39. 39.325 + 417 =
  40. 40.571 + 662 =

Answer key

  1. 709
  2. 206
  3. 324
  4. 1219
  5. 170
  6. 561
  7. 270
  8. 242
  9. 995
  10. 423
  11. 574
  12. 746
  13. 990
  14. 431
  15. 189
  16. 1018
  17. 640
  18. 839
  19. 952
  20. 1107
  21. 708
  22. 532
  23. 209
  24. 272
  25. 148
  26. 222
  27. 482
  28. 796
  29. 209
  30. 517
  31. 956
  32. 469
  33. 681
  34. 1071
  35. 133
  36. 704
  37. 341
  38. 1010
  39. 742
  40. 1233

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