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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 878 · 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. 1.661 − 123 =
  2. 2.792 − 245 =
  3. 3.938 − 809 =
  4. 4.232 + 398 =
  5. 5.228 + 545 =
  6. 6.803 − 579 =
  7. 7.527 − 272 =
  8. 8.261 + 386 =
  9. 9.464 + 267 =
  10. 10.742 − 251 =
  11. 11.888 − 701 =
  12. 12.157 + 395 =
  13. 13.871 − 362 =
  14. 14.768 − 364 =
  15. 15.533 − 217 =
  16. 16.644 + 296 =
  17. 17.681 − 557 =
  18. 18.823 − 652 =
  19. 19.754 + 575 =
  20. 20.185 + 368 =
  21. 21.546 − 208 =
  22. 22.532 − 266 =
  23. 23.350 + 644 =
  24. 24.695 + 235 =
  25. 25.942 − 708 =
  26. 26.657 − 476 =
  27. 27.215 + 544 =
  28. 28.572 − 218 =
  29. 29.543 + 487 =
  30. 30.617 + 278 =
  31. 31.985 − 844 =
  32. 32.505 − 133 =
  33. 33.796 − 518 =
  34. 34.513 − 267 =
  35. 35.271 + 307 =
  36. 36.301 + 675 =
  37. 37.235 + 173 =
  38. 38.702 + 125 =
  39. 39.796 − 409 =
  40. 40.281 + 213 =

Answer key

  1. 538
  2. 547
  3. 129
  4. 630
  5. 773
  6. 224
  7. 255
  8. 647
  9. 731
  10. 491
  11. 187
  12. 552
  13. 509
  14. 404
  15. 316
  16. 940
  17. 124
  18. 171
  19. 1329
  20. 553
  21. 338
  22. 266
  23. 994
  24. 930
  25. 234
  26. 181
  27. 759
  28. 354
  29. 1030
  30. 895
  31. 141
  32. 372
  33. 278
  34. 246
  35. 578
  36. 976
  37. 408
  38. 827
  39. 387
  40. 494

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