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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 138 · 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. 1.479 − 271 =
  2. 2.926 − 374 =
  3. 3.594 + 433 =
  4. 4.706 + 187 =
  5. 5.829 − 522 =
  6. 6.516 − 347 =
  7. 7.653 + 386 =
  8. 8.431 + 219 =
  9. 9.526 + 333 =
  10. 10.307 + 365 =
  11. 11.808 − 436 =
  12. 12.125 + 334 =
  13. 13.219 + 419 =
  14. 14.785 − 613 =
  15. 15.204 + 653 =
  16. 16.618 − 143 =
  17. 17.290 + 654 =
  18. 18.944 − 821 =
  19. 19.640 + 618 =
  20. 20.785 − 305 =
  21. 21.580 − 281 =
  22. 22.755 − 134 =
  23. 23.365 + 535 =
  24. 24.886 − 497 =
  25. 25.537 + 358 =
  26. 26.442 − 126 =
  27. 27.179 + 123 =
  28. 28.441 − 328 =
  29. 29.593 − 244 =
  30. 30.768 + 257 =
  31. 31.684 − 205 =
  32. 32.633 − 454 =
  33. 33.692 − 351 =
  34. 34.434 + 559 =
  35. 35.535 + 271 =
  36. 36.737 + 671 =
  37. 37.374 + 234 =
  38. 38.968 − 241 =
  39. 39.653 − 488 =
  40. 40.571 + 454 =

Answer key

  1. 208
  2. 552
  3. 1027
  4. 893
  5. 307
  6. 169
  7. 1039
  8. 650
  9. 859
  10. 672
  11. 372
  12. 459
  13. 638
  14. 172
  15. 857
  16. 475
  17. 944
  18. 123
  19. 1258
  20. 480
  21. 299
  22. 621
  23. 900
  24. 389
  25. 895
  26. 316
  27. 302
  28. 113
  29. 349
  30. 1025
  31. 479
  32. 179
  33. 341
  34. 993
  35. 806
  36. 1408
  37. 608
  38. 727
  39. 165
  40. 1025

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