[Free Steem!] Mathematics × Programming Competition #1

Welcome to the

1st Mathematics × Programming Competition!

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Question

Difficulty index: 4 / 10

Kenchung has 90 SBD and goes to a store to buy stationery. A pencil costs 9 SBD and a pen costs 10 SBD. How many different possible combinations are there for the stationery he purchased? (Buying nothing at all is not considered as a combination) (He does not have to use all the money)

Photo source: www.matthewdeevers.com

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Answer submission

• Please submit through this link.
• You are not required to show your steps. You can use either a mathematical or programming approach.
• This competition will last for 24 hours. After that no more submission would be accepted.

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Rules

• Participants who submit the answer as a comment below this post will be disqualified.
• Each participant can only submit once. In case of duplicated submission, the latest answer will be considered.
• You have to upvote this post AND the announcement post in order to be eligible for the competition.

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Prizes

• The final SBD payout of the previous post would be added to the prize pool. The prize pool contains 0 SBD at this moment.
• The first participant who gave the correct answer will get 75% of the prize pool.
• Other participants who got the correct answers will enter a lucky draw. Those who resteemed this post will have 400% higher chance to win! The 5 winners will share 25% of the prize pool.
• If not all prizes are given out, they will be accumulated for the next competition!
• @kenchung reserve all the rights to disqualify any suspected cheating players and decide the distribution of prize among the winner(s).

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