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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 527 · 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. 1.640 + 464 =
  2. 2.281 + 163 =
  3. 3.955 − 404 =
  4. 4.567 + 625 =
  5. 5.960 − 305 =
  6. 6.485 − 297 =
  7. 7.195 + 221 =
  8. 8.585 + 501 =
  9. 9.232 + 518 =
  10. 10.477 − 285 =
  11. 11.620 + 472 =
  12. 12.647 + 166 =
  13. 13.355 + 383 =
  14. 14.124 + 375 =
  15. 15.217 + 239 =
  16. 16.580 − 264 =
  17. 17.872 − 221 =
  18. 18.782 + 452 =
  19. 19.668 + 232 =
  20. 20.496 + 551 =
  21. 21.899 − 644 =
  22. 22.606 + 125 =
  23. 23.579 − 428 =
  24. 24.797 − 643 =
  25. 25.935 − 413 =
  26. 26.783 + 525 =
  27. 27.780 − 245 =
  28. 28.884 − 192 =
  29. 29.335 + 593 =
  30. 30.438 − 268 =
  31. 31.165 + 621 =
  32. 32.629 − 354 =
  33. 33.680 − 401 =
  34. 34.167 + 399 =
  35. 35.741 − 542 =
  36. 36.537 − 286 =
  37. 37.508 + 633 =
  38. 38.579 + 469 =
  39. 39.491 − 167 =
  40. 40.623 + 206 =

Answer key

  1. 1104
  2. 444
  3. 551
  4. 1192
  5. 655
  6. 188
  7. 416
  8. 1086
  9. 750
  10. 192
  11. 1092
  12. 813
  13. 738
  14. 499
  15. 456
  16. 316
  17. 651
  18. 1234
  19. 900
  20. 1047
  21. 255
  22. 731
  23. 151
  24. 154
  25. 522
  26. 1308
  27. 535
  28. 692
  29. 928
  30. 170
  31. 786
  32. 275
  33. 279
  34. 566
  35. 199
  36. 251
  37. 1141
  38. 1048
  39. 324
  40. 829

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