20CS110001  Introduction to Computer Science  Fall 2010 

Pencil Prices Puzzle
The price of pencils has skyrocketed in recent years. Each year the
price has increased, and for the last seven years (including this
year) the new price is the sum of the prices for the two previous
years. Last year, a pencil cost $0.60.
How much does a pencil cost today? How much did a pencil cost seven years ago? 

solution 