MathNet 2015-part-02 — 191 problems (EN–VI) Question 16

Ten chairs are arranged around a round table and marked with numbers $1$ to $10$ successively (in such a way that chairs $1$ and $10$ are also adjacent), and a knight is sitting in each chair. In the beginning, every knight has an even number of coins. Simultaneously, each knight gives half of his coins to his left neighbour, and the other half to his right neighbour. After that, the knight sitting in chair $1$ has $22$ coins, and each succeeding knight has two more coins, up until the knight in chair $10$ that has $40$ coins.

How many coins did the knight that ended up with $36$ coins have in the beginning? (Hong Kong)