An eccentric uncle has left a fortune to you and your brother - with a very strange condition.
He's bequeathed to you his special fake coin that lands heads more often than it lands tails. And all his money will go either to you or to your brother depending on who wins a sequence of tosses of his special coin.
What method can you and your brother devise so that you'll both agree that a fair winner has been determined by repeated tosses of the biased coin? It's unlikely that more than 26 tosses would be required.