DAY 475

A man went into a bank with exactly $1,000, all in one-dollar bills. He gave the money to a cashier and said, "Put this money into ten bags in such a way that if I call and ask for a certain number of dollars, you can hand me over one or more bags, giving me the exact amount called for, without having to open any of the bags."

How was the cashier to do this?

Answer:

 

The contents of the bags should be $1, $2, $4, $8, $16, $32, $64, $128, $256, and $489. Notice how the contents of the first nine bags are in geometric progression.