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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 45 · 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. 1.284 + 182 =
  2. 2.266 + 194 =
  3. 3.617 − 147 =
  4. 4.899 − 772 =
  5. 5.477 − 261 =
  6. 6.764 + 557 =
  7. 7.391 + 408 =
  8. 8.601 + 634 =
  9. 9.298 + 411 =
  10. 10.581 − 161 =
  11. 11.432 − 171 =
  12. 12.972 − 147 =
  13. 13.421 + 596 =
  14. 14.520 + 597 =
  15. 15.416 − 268 =
  16. 16.728 − 317 =
  17. 17.861 − 301 =
  18. 18.933 − 141 =
  19. 19.691 − 584 =
  20. 20.687 − 212 =
  21. 21.466 + 685 =
  22. 22.650 − 281 =
  23. 23.599 + 253 =
  24. 24.546 − 191 =
  25. 25.578 − 207 =
  26. 26.589 − 175 =
  27. 27.369 + 541 =
  28. 28.153 + 188 =
  29. 29.592 − 453 =
  30. 30.153 + 379 =
  31. 31.959 − 498 =
  32. 32.418 + 352 =
  33. 33.598 − 187 =
  34. 34.500 − 137 =
  35. 35.131 + 119 =
  36. 36.406 + 405 =
  37. 37.731 − 178 =
  38. 38.538 + 573 =
  39. 39.864 − 248 =
  40. 40.512 + 565 =

Answer key

  1. 466
  2. 460
  3. 470
  4. 127
  5. 216
  6. 1321
  7. 799
  8. 1235
  9. 709
  10. 420
  11. 261
  12. 825
  13. 1017
  14. 1117
  15. 148
  16. 411
  17. 560
  18. 792
  19. 107
  20. 475
  21. 1151
  22. 369
  23. 852
  24. 355
  25. 371
  26. 414
  27. 910
  28. 341
  29. 139
  30. 532
  31. 461
  32. 770
  33. 411
  34. 363
  35. 250
  36. 811
  37. 553
  38. 1111
  39. 616
  40. 1077

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