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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 275 · 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. 1.613 − 402 =
  2. 2.757 + 349 =
  3. 3.942 − 197 =
  4. 4.421 + 257 =
  5. 5.483 + 144 =
  6. 6.640 − 521 =
  7. 7.417 − 253 =
  8. 8.275 + 329 =
  9. 9.241 + 388 =
  10. 10.156 + 155 =
  11. 11.452 − 179 =
  12. 12.749 + 155 =
  13. 13.201 + 246 =
  14. 14.246 + 211 =
  15. 15.905 − 712 =
  16. 16.235 + 514 =
  17. 17.518 + 236 =
  18. 18.896 − 521 =
  19. 19.948 − 771 =
  20. 20.781 + 521 =
  21. 21.369 + 564 =
  22. 22.753 + 652 =
  23. 23.425 − 254 =
  24. 24.340 + 671 =
  25. 25.465 − 281 =
  26. 26.980 − 699 =
  27. 27.593 − 355 =
  28. 28.469 − 186 =
  29. 29.718 + 214 =
  30. 30.927 − 326 =
  31. 31.676 + 433 =
  32. 32.687 + 639 =
  33. 33.586 − 186 =
  34. 34.664 − 164 =
  35. 35.459 + 135 =
  36. 36.190 + 351 =
  37. 37.785 + 342 =
  38. 38.151 + 211 =
  39. 39.440 − 258 =
  40. 40.962 − 672 =

Answer key

  1. 211
  2. 1106
  3. 745
  4. 678
  5. 627
  6. 119
  7. 164
  8. 604
  9. 629
  10. 311
  11. 273
  12. 904
  13. 447
  14. 457
  15. 193
  16. 749
  17. 754
  18. 375
  19. 177
  20. 1302
  21. 933
  22. 1405
  23. 171
  24. 1011
  25. 184
  26. 281
  27. 238
  28. 283
  29. 932
  30. 601
  31. 1109
  32. 1326
  33. 400
  34. 500
  35. 594
  36. 541
  37. 1127
  38. 362
  39. 182
  40. 290

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