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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 369 · 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. 1.509 + 217 =
  2. 2.959 − 175 =
  3. 3.710 − 384 =
  4. 4.953 − 573 =
  5. 5.388 + 622 =
  6. 6.492 − 269 =
  7. 7.774 − 243 =
  8. 8.393 + 464 =
  9. 9.557 − 375 =
  10. 10.353 + 314 =
  11. 11.817 − 219 =
  12. 12.778 − 158 =
  13. 13.625 + 371 =
  14. 14.140 + 382 =
  15. 15.651 + 339 =
  16. 16.306 + 534 =
  17. 17.734 − 418 =
  18. 18.916 − 717 =
  19. 19.148 + 345 =
  20. 20.809 − 421 =
  21. 21.458 + 411 =
  22. 22.439 − 303 =
  23. 23.669 − 121 =
  24. 24.747 + 373 =
  25. 25.312 + 126 =
  26. 26.779 − 191 =
  27. 27.378 + 156 =
  28. 28.446 − 315 =
  29. 29.278 + 209 =
  30. 30.458 + 177 =
  31. 31.276 + 237 =
  32. 32.439 − 156 =
  33. 33.790 − 311 =
  34. 34.547 − 121 =
  35. 35.688 + 218 =
  36. 36.433 + 346 =
  37. 37.540 + 163 =
  38. 38.227 + 518 =
  39. 39.482 − 363 =
  40. 40.781 − 369 =

Answer key

  1. 726
  2. 784
  3. 326
  4. 380
  5. 1010
  6. 223
  7. 531
  8. 857
  9. 182
  10. 667
  11. 598
  12. 620
  13. 996
  14. 522
  15. 990
  16. 840
  17. 316
  18. 199
  19. 493
  20. 388
  21. 869
  22. 136
  23. 548
  24. 1120
  25. 438
  26. 588
  27. 534
  28. 131
  29. 487
  30. 635
  31. 513
  32. 283
  33. 479
  34. 426
  35. 906
  36. 779
  37. 703
  38. 745
  39. 119
  40. 412

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