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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 177 · 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. 1.630 − 531 =
  2. 2.684 − 281 =
  3. 3.921 − 437 =
  4. 4.416 + 631 =
  5. 5.434 + 411 =
  6. 6.489 − 293 =
  7. 7.291 + 628 =
  8. 8.227 + 161 =
  9. 9.247 + 357 =
  10. 10.636 − 159 =
  11. 11.686 + 579 =
  12. 12.494 − 185 =
  13. 13.919 − 394 =
  14. 14.482 − 288 =
  15. 15.319 + 661 =
  16. 16.288 + 236 =
  17. 17.818 − 505 =
  18. 18.675 − 215 =
  19. 19.968 − 286 =
  20. 20.717 − 116 =
  21. 21.923 − 733 =
  22. 22.803 − 186 =
  23. 23.163 + 516 =
  24. 24.523 − 297 =
  25. 25.507 + 131 =
  26. 26.772 + 574 =
  27. 27.135 + 256 =
  28. 28.791 − 653 =
  29. 29.809 − 234 =
  30. 30.573 − 337 =
  31. 31.157 + 156 =
  32. 32.565 − 183 =
  33. 33.759 + 502 =
  34. 34.653 + 196 =
  35. 35.982 − 627 =
  36. 36.259 + 604 =
  37. 37.377 + 281 =
  38. 38.554 − 122 =
  39. 39.812 − 621 =
  40. 40.348 + 223 =

Answer key

  1. 99
  2. 403
  3. 484
  4. 1047
  5. 845
  6. 196
  7. 919
  8. 388
  9. 604
  10. 477
  11. 1265
  12. 309
  13. 525
  14. 194
  15. 980
  16. 524
  17. 313
  18. 460
  19. 682
  20. 601
  21. 190
  22. 617
  23. 679
  24. 226
  25. 638
  26. 1346
  27. 391
  28. 138
  29. 575
  30. 236
  31. 313
  32. 382
  33. 1261
  34. 849
  35. 355
  36. 863
  37. 658
  38. 432
  39. 191
  40. 571

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