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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 563 · 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. 1.450 − 142 =
  2. 2.126 + 658 =
  3. 3.549 + 164 =
  4. 4.738 + 511 =
  5. 5.386 + 226 =
  6. 6.615 + 255 =
  7. 7.421 − 209 =
  8. 8.579 − 296 =
  9. 9.184 + 445 =
  10. 10.282 + 638 =
  11. 11.536 + 611 =
  12. 12.224 + 275 =
  13. 13.416 − 215 =
  14. 14.789 − 638 =
  15. 15.434 − 332 =
  16. 16.673 + 337 =
  17. 17.550 − 425 =
  18. 18.896 − 702 =
  19. 19.125 + 117 =
  20. 20.253 + 241 =
  21. 21.462 + 554 =
  22. 22.488 + 672 =
  23. 23.308 + 272 =
  24. 24.529 − 261 =
  25. 25.548 + 253 =
  26. 26.437 + 218 =
  27. 27.361 + 194 =
  28. 28.387 + 427 =
  29. 29.896 − 466 =
  30. 30.524 − 401 =
  31. 31.509 + 371 =
  32. 32.567 − 438 =
  33. 33.632 + 269 =
  34. 34.752 − 238 =
  35. 35.614 + 257 =
  36. 36.951 − 659 =
  37. 37.664 − 191 =
  38. 38.653 − 239 =
  39. 39.972 − 231 =
  40. 40.789 + 236 =

Answer key

  1. 308
  2. 784
  3. 713
  4. 1249
  5. 612
  6. 870
  7. 212
  8. 283
  9. 629
  10. 920
  11. 1147
  12. 499
  13. 201
  14. 151
  15. 102
  16. 1010
  17. 125
  18. 194
  19. 242
  20. 494
  21. 1016
  22. 1160
  23. 580
  24. 268
  25. 801
  26. 655
  27. 555
  28. 814
  29. 430
  30. 123
  31. 880
  32. 129
  33. 901
  34. 514
  35. 871
  36. 292
  37. 473
  38. 414
  39. 741
  40. 1025

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