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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 225 · 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. 1.587 − 371 =
  2. 2.492 − 236 =
  3. 3.456 − 161 =
  4. 4.666 + 119 =
  5. 5.545 + 451 =
  6. 6.688 + 179 =
  7. 7.317 + 141 =
  8. 8.599 + 471 =
  9. 9.215 + 674 =
  10. 10.428 − 182 =
  11. 11.679 − 143 =
  12. 12.289 + 173 =
  13. 13.868 − 568 =
  14. 14.642 − 412 =
  15. 15.817 − 577 =
  16. 16.553 − 271 =
  17. 17.307 + 191 =
  18. 18.454 + 585 =
  19. 19.313 + 313 =
  20. 20.263 + 131 =
  21. 21.550 − 287 =
  22. 22.215 + 229 =
  23. 23.544 − 121 =
  24. 24.444 + 201 =
  25. 25.729 + 151 =
  26. 26.297 + 334 =
  27. 27.902 − 143 =
  28. 28.299 + 399 =
  29. 29.416 + 674 =
  30. 30.188 + 112 =
  31. 31.145 + 611 =
  32. 32.301 + 147 =
  33. 33.190 + 464 =
  34. 34.304 + 284 =
  35. 35.522 − 204 =
  36. 36.358 + 626 =
  37. 37.151 + 125 =
  38. 38.615 − 136 =
  39. 39.394 + 531 =
  40. 40.872 − 639 =

Answer key

  1. 216
  2. 256
  3. 295
  4. 785
  5. 996
  6. 867
  7. 458
  8. 1070
  9. 889
  10. 246
  11. 536
  12. 462
  13. 300
  14. 230
  15. 240
  16. 282
  17. 498
  18. 1039
  19. 626
  20. 394
  21. 263
  22. 444
  23. 423
  24. 645
  25. 880
  26. 631
  27. 759
  28. 698
  29. 1090
  30. 300
  31. 756
  32. 448
  33. 654
  34. 588
  35. 318
  36. 984
  37. 276
  38. 479
  39. 925
  40. 233

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