Timmy went into a store and said "I'll buy that calculator for $10 if you lend me as much money as I have in my pocket. The clerk lent him the money and Timmy gave him $10 cash. He went to the next store and bought a $10 cap using the same gambit. Then he bought a $10 umbrella with the same strategy. When he paid for the umbrella, he had no money left. How much did he start out with?