The following problem is a bit of a classic. It can be found in George Polya's How to Solve It:
Among Grandfather's papers a bill was found:
The first and last digit of the number that obviously represented the total price of those fowls are illegible and are replaced here by underscores. What are the two faded digits and what was the price of one turkey?72 turkeys $_67.9_
For the solution, see the answers page.