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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 696 · 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. 1.553 + 375 =
  2. 2.152 + 639 =
  3. 3.692 − 271 =
  4. 4.222 + 405 =
  5. 5.778 + 573 =
  6. 6.731 + 441 =
  7. 7.661 + 412 =
  8. 8.195 + 445 =
  9. 9.750 + 138 =
  10. 10.651 − 216 =
  11. 11.801 − 247 =
  12. 12.507 + 542 =
  13. 13.130 + 122 =
  14. 14.913 − 305 =
  15. 15.618 + 297 =
  16. 16.779 + 647 =
  17. 17.468 − 201 =
  18. 18.495 + 652 =
  19. 19.508 + 461 =
  20. 20.300 + 343 =
  21. 21.509 + 574 =
  22. 22.325 + 241 =
  23. 23.755 + 272 =
  24. 24.144 + 117 =
  25. 25.204 + 135 =
  26. 26.534 + 454 =
  27. 27.234 + 575 =
  28. 28.766 + 287 =
  29. 29.479 − 134 =
  30. 30.216 + 385 =
  31. 31.581 − 381 =
  32. 32.483 + 126 =
  33. 33.751 − 525 =
  34. 34.169 + 268 =
  35. 35.236 + 355 =
  36. 36.546 − 116 =
  37. 37.516 − 133 =
  38. 38.612 − 323 =
  39. 39.899 − 742 =
  40. 40.434 + 298 =

Answer key

  1. 928
  2. 791
  3. 421
  4. 627
  5. 1351
  6. 1172
  7. 1073
  8. 640
  9. 888
  10. 435
  11. 554
  12. 1049
  13. 252
  14. 608
  15. 915
  16. 1426
  17. 267
  18. 1147
  19. 969
  20. 643
  21. 1083
  22. 566
  23. 1027
  24. 261
  25. 339
  26. 988
  27. 809
  28. 1053
  29. 345
  30. 601
  31. 200
  32. 609
  33. 226
  34. 437
  35. 591
  36. 430
  37. 383
  38. 289
  39. 157
  40. 732

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