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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 875 · 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. 1.517 + 631 =
  2. 2.551 + 187 =
  3. 3.869 − 281 =
  4. 4.521 + 441 =
  5. 5.723 − 215 =
  6. 6.467 − 222 =
  7. 7.489 + 187 =
  8. 8.580 − 126 =
  9. 9.163 + 688 =
  10. 10.967 − 459 =
  11. 11.308 + 135 =
  12. 12.503 + 481 =
  13. 13.442 − 316 =
  14. 14.438 − 136 =
  15. 15.757 − 378 =
  16. 16.284 + 195 =
  17. 17.646 + 411 =
  18. 18.898 − 413 =
  19. 19.459 − 335 =
  20. 20.509 + 532 =
  21. 21.308 + 161 =
  22. 22.623 − 221 =
  23. 23.525 − 151 =
  24. 24.542 − 255 =
  25. 25.252 + 333 =
  26. 26.447 − 318 =
  27. 27.481 + 221 =
  28. 28.469 + 634 =
  29. 29.221 + 244 =
  30. 30.531 − 277 =
  31. 31.822 − 594 =
  32. 32.407 + 221 =
  33. 33.416 − 277 =
  34. 34.646 + 371 =
  35. 35.748 + 228 =
  36. 36.725 − 284 =
  37. 37.376 + 297 =
  38. 38.360 + 466 =
  39. 39.729 + 621 =
  40. 40.793 − 638 =

Answer key

  1. 1148
  2. 738
  3. 588
  4. 962
  5. 508
  6. 245
  7. 676
  8. 454
  9. 851
  10. 508
  11. 443
  12. 984
  13. 126
  14. 302
  15. 379
  16. 479
  17. 1057
  18. 485
  19. 124
  20. 1041
  21. 469
  22. 402
  23. 374
  24. 287
  25. 585
  26. 129
  27. 702
  28. 1103
  29. 465
  30. 254
  31. 228
  32. 628
  33. 139
  34. 1017
  35. 976
  36. 441
  37. 673
  38. 826
  39. 1350
  40. 155

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