Holding a contest

Last week, I went to a restaurant. There was a / They were holding a contest about a bowl full of marbles. My friend and I guessed some numbers. However, the person who won was a man who was crunching some numbers. He did a calculation / some calculations in his head and came out with the magic number. It was a game, and everyone is supposed to guess a number. My friend thought that man was cheating. However, he only was using what God gave to him to beat us out of a prize for winning the game.

Bom dia Vinicius, muito bom! Just a few small mistakes but I understood everything perfectly :)