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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 795 · 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. 1.290 + 215 =
  2. 2.549 − 333 =
  3. 3.420 + 117 =
  4. 4.989 − 751 =
  5. 5.576 + 652 =
  6. 6.783 + 673 =
  7. 7.561 − 199 =
  8. 8.221 + 476 =
  9. 9.254 + 278 =
  10. 10.403 + 489 =
  11. 11.821 − 445 =
  12. 12.328 + 321 =
  13. 13.640 + 571 =
  14. 14.768 − 452 =
  15. 15.252 + 661 =
  16. 16.937 − 504 =
  17. 17.471 + 339 =
  18. 18.411 + 445 =
  19. 19.970 − 334 =
  20. 20.586 + 605 =
  21. 21.291 + 654 =
  22. 22.202 + 346 =
  23. 23.727 + 171 =
  24. 24.786 − 559 =
  25. 25.750 − 551 =
  26. 26.600 − 491 =
  27. 27.299 + 394 =
  28. 28.804 − 215 =
  29. 29.423 + 479 =
  30. 30.551 + 409 =
  31. 31.613 + 449 =
  32. 32.723 − 158 =
  33. 33.839 − 505 =
  34. 34.252 + 169 =
  35. 35.593 + 288 =
  36. 36.761 − 381 =
  37. 37.698 − 151 =
  38. 38.414 − 284 =
  39. 39.727 + 512 =
  40. 40.202 + 678 =

Answer key

  1. 505
  2. 216
  3. 537
  4. 238
  5. 1228
  6. 1456
  7. 362
  8. 697
  9. 532
  10. 892
  11. 376
  12. 649
  13. 1211
  14. 316
  15. 913
  16. 433
  17. 810
  18. 856
  19. 636
  20. 1191
  21. 945
  22. 548
  23. 898
  24. 227
  25. 199
  26. 109
  27. 693
  28. 589
  29. 902
  30. 960
  31. 1062
  32. 565
  33. 334
  34. 421
  35. 881
  36. 380
  37. 547
  38. 130
  39. 1239
  40. 880

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