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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 404 · 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. 1.545 − 394 =
  2. 2.147 + 411 =
  3. 3.422 − 153 =
  4. 4.463 − 134 =
  5. 5.355 + 596 =
  6. 6.413 + 381 =
  7. 7.508 + 676 =
  8. 8.253 + 423 =
  9. 9.696 − 196 =
  10. 10.506 + 502 =
  11. 11.530 + 113 =
  12. 12.524 + 157 =
  13. 13.124 + 363 =
  14. 14.675 + 511 =
  15. 15.547 + 291 =
  16. 16.271 + 212 =
  17. 17.920 − 146 =
  18. 18.800 − 397 =
  19. 19.340 + 399 =
  20. 20.412 + 156 =
  21. 21.156 + 117 =
  22. 22.147 + 251 =
  23. 23.882 − 159 =
  24. 24.527 − 158 =
  25. 25.380 + 434 =
  26. 26.786 + 171 =
  27. 27.567 − 332 =
  28. 28.608 − 494 =
  29. 29.927 − 779 =
  30. 30.655 + 178 =
  31. 31.777 + 401 =
  32. 32.408 + 624 =
  33. 33.256 + 491 =
  34. 34.441 + 167 =
  35. 35.318 + 594 =
  36. 36.494 − 303 =
  37. 37.771 − 274 =
  38. 38.645 − 497 =
  39. 39.569 + 274 =
  40. 40.476 + 191 =

Answer key

  1. 151
  2. 558
  3. 269
  4. 329
  5. 951
  6. 794
  7. 1184
  8. 676
  9. 500
  10. 1008
  11. 643
  12. 681
  13. 487
  14. 1186
  15. 838
  16. 483
  17. 774
  18. 403
  19. 739
  20. 568
  21. 273
  22. 398
  23. 723
  24. 369
  25. 814
  26. 957
  27. 235
  28. 114
  29. 148
  30. 833
  31. 1178
  32. 1032
  33. 747
  34. 608
  35. 912
  36. 191
  37. 497
  38. 148
  39. 843
  40. 667

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