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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 924 · 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. 1.947 − 251 =
  2. 2.630 − 488 =
  3. 3.950 − 831 =
  4. 4.440 − 233 =
  5. 5.655 + 686 =
  6. 6.413 − 246 =
  7. 7.165 + 251 =
  8. 8.204 + 245 =
  9. 9.736 − 149 =
  10. 10.553 + 168 =
  11. 11.526 − 304 =
  12. 12.244 + 599 =
  13. 13.440 − 172 =
  14. 14.380 + 177 =
  15. 15.676 + 258 =
  16. 16.793 − 644 =
  17. 17.340 + 598 =
  18. 18.178 + 271 =
  19. 19.645 + 602 =
  20. 20.182 + 659 =
  21. 21.720 − 598 =
  22. 22.971 − 312 =
  23. 23.696 − 433 =
  24. 24.893 − 204 =
  25. 25.295 + 322 =
  26. 26.492 + 244 =
  27. 27.606 + 231 =
  28. 28.696 + 183 =
  29. 29.287 + 157 =
  30. 30.815 − 424 =
  31. 31.376 + 272 =
  32. 32.427 − 241 =
  33. 33.498 + 664 =
  34. 34.554 − 436 =
  35. 35.607 − 433 =
  36. 36.439 − 141 =
  37. 37.707 − 305 =
  38. 38.857 − 356 =
  39. 39.881 − 696 =
  40. 40.533 − 321 =

Answer key

  1. 696
  2. 142
  3. 119
  4. 207
  5. 1341
  6. 167
  7. 416
  8. 449
  9. 587
  10. 721
  11. 222
  12. 843
  13. 268
  14. 557
  15. 934
  16. 149
  17. 938
  18. 449
  19. 1247
  20. 841
  21. 122
  22. 659
  23. 263
  24. 689
  25. 617
  26. 736
  27. 837
  28. 879
  29. 444
  30. 391
  31. 648
  32. 186
  33. 1162
  34. 118
  35. 174
  36. 298
  37. 402
  38. 501
  39. 185
  40. 212

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