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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 238 · 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. 1.750 + 296 =
  2. 2.635 − 192 =
  3. 3.788 − 271 =
  4. 4.537 + 281 =
  5. 5.746 − 604 =
  6. 6.767 + 638 =
  7. 7.491 + 231 =
  8. 8.833 − 586 =
  9. 9.527 + 144 =
  10. 10.584 − 129 =
  11. 11.646 − 194 =
  12. 12.462 − 143 =
  13. 13.519 − 351 =
  14. 14.284 + 222 =
  15. 15.572 + 222 =
  16. 16.527 − 319 =
  17. 17.720 − 135 =
  18. 18.599 + 225 =
  19. 19.505 − 151 =
  20. 20.621 − 396 =
  21. 21.376 + 604 =
  22. 22.300 + 218 =
  23. 23.675 − 426 =
  24. 24.644 + 642 =
  25. 25.788 − 352 =
  26. 26.180 + 468 =
  27. 27.746 + 246 =
  28. 28.696 + 589 =
  29. 29.781 + 644 =
  30. 30.550 − 406 =
  31. 31.821 − 666 =
  32. 32.373 + 638 =
  33. 33.215 + 287 =
  34. 34.244 + 541 =
  35. 35.919 − 227 =
  36. 36.448 − 268 =
  37. 37.897 − 238 =
  38. 38.731 − 352 =
  39. 39.484 − 371 =
  40. 40.596 + 453 =

Answer key

  1. 1046
  2. 443
  3. 517
  4. 818
  5. 142
  6. 1405
  7. 722
  8. 247
  9. 671
  10. 455
  11. 452
  12. 319
  13. 168
  14. 506
  15. 794
  16. 208
  17. 585
  18. 824
  19. 354
  20. 225
  21. 980
  22. 518
  23. 249
  24. 1286
  25. 436
  26. 648
  27. 992
  28. 1285
  29. 1425
  30. 144
  31. 155
  32. 1011
  33. 502
  34. 785
  35. 692
  36. 180
  37. 659
  38. 379
  39. 113
  40. 1049

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