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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 601 · 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. 1.173 + 221 =
  2. 2.919 − 187 =
  3. 3.505 − 139 =
  4. 4.701 − 216 =
  5. 5.186 + 397 =
  6. 6.778 + 388 =
  7. 7.153 + 418 =
  8. 8.870 − 533 =
  9. 9.651 + 166 =
  10. 10.264 + 376 =
  11. 11.716 − 123 =
  12. 12.350 + 289 =
  13. 13.677 + 316 =
  14. 14.773 − 418 =
  15. 15.560 + 661 =
  16. 16.743 + 396 =
  17. 17.343 + 271 =
  18. 18.641 + 301 =
  19. 19.509 − 311 =
  20. 20.602 + 405 =
  21. 21.794 − 168 =
  22. 22.175 + 448 =
  23. 23.831 − 145 =
  24. 24.689 + 403 =
  25. 25.126 + 389 =
  26. 26.862 − 526 =
  27. 27.295 + 404 =
  28. 28.639 − 216 =
  29. 29.831 − 325 =
  30. 30.631 + 362 =
  31. 31.819 − 199 =
  32. 32.575 + 575 =
  33. 33.863 − 255 =
  34. 34.124 + 356 =
  35. 35.123 + 588 =
  36. 36.328 + 444 =
  37. 37.295 + 112 =
  38. 38.236 + 171 =
  39. 39.386 + 325 =
  40. 40.571 − 237 =

Answer key

  1. 394
  2. 732
  3. 366
  4. 485
  5. 583
  6. 1166
  7. 571
  8. 337
  9. 817
  10. 640
  11. 593
  12. 639
  13. 993
  14. 355
  15. 1221
  16. 1139
  17. 614
  18. 942
  19. 198
  20. 1007
  21. 626
  22. 623
  23. 686
  24. 1092
  25. 515
  26. 336
  27. 699
  28. 423
  29. 506
  30. 993
  31. 620
  32. 1150
  33. 608
  34. 480
  35. 711
  36. 772
  37. 407
  38. 407
  39. 711
  40. 334

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