Paying with coins

Task number: 2800

Show that every integral sum greater than or equal to 8 crowns can be paid with 5-crown and/or 3-crown coins.

  • Resolution

    \(8=3+5\), \(9=3+3+3\), \(10=5+5\). For \(n\ge 11\) we use the inductive assumption that it is possible to pay \(n-3\), and we add one 3-crown coin.

Difficulty level: Easy task (using definitions and simple reasoning)
Solution require uncommon idea
Cs translation
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