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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 204 · 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. 1.399 + 152 =
  2. 2.535 + 219 =
  3. 3.682 − 529 =
  4. 4.570 + 671 =
  5. 5.585 + 299 =
  6. 6.651 + 604 =
  7. 7.220 + 482 =
  8. 8.619 − 288 =
  9. 9.343 + 471 =
  10. 10.521 − 275 =
  11. 11.268 + 234 =
  12. 12.367 + 172 =
  13. 13.568 − 181 =
  14. 14.763 − 611 =
  15. 15.837 − 719 =
  16. 16.337 + 142 =
  17. 17.808 − 378 =
  18. 18.735 + 272 =
  19. 19.590 − 187 =
  20. 20.667 + 457 =
  21. 21.601 + 651 =
  22. 22.322 + 421 =
  23. 23.415 + 461 =
  24. 24.809 − 359 =
  25. 25.597 + 424 =
  26. 26.872 − 266 =
  27. 27.215 + 241 =
  28. 28.585 + 531 =
  29. 29.697 + 643 =
  30. 30.593 + 122 =
  31. 31.584 + 151 =
  32. 32.579 + 507 =
  33. 33.580 − 476 =
  34. 34.366 + 129 =
  35. 35.688 + 315 =
  36. 36.737 − 338 =
  37. 37.616 − 357 =
  38. 38.496 + 239 =
  39. 39.755 + 542 =
  40. 40.556 − 169 =

Answer key

  1. 551
  2. 754
  3. 153
  4. 1241
  5. 884
  6. 1255
  7. 702
  8. 331
  9. 814
  10. 246
  11. 502
  12. 539
  13. 387
  14. 152
  15. 118
  16. 479
  17. 430
  18. 1007
  19. 403
  20. 1124
  21. 1252
  22. 743
  23. 876
  24. 450
  25. 1021
  26. 606
  27. 456
  28. 1116
  29. 1340
  30. 715
  31. 735
  32. 1086
  33. 104
  34. 495
  35. 1003
  36. 399
  37. 259
  38. 735
  39. 1297
  40. 387

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