Some OO Design
"The critical design tool for software development is a mind well educated in design principles. It is not the UML or any other technology." - Craig Larman I've recently found the following interview question on stackoverflow : Basic sales tax is applicable at a rate of 10% on all goods, except books, food, and medical products that are exempt. Import duty is an additional sales tax applicable on all imported goods at a rate of 5%, with no exemptions. When I purchase items I receive a receipt which lists the name of all the items and their price (including tax), finishing with the total cost of the items, and the total amounts of sales taxes paid. The rounding rules for sales tax are that for a tax rate of n%, a shelf price of p contains (np/100 rounded up to the nearest 0.05) amount of sales tax. This is a very familiar example that can be used as a really good gauge of various software development skills. There are many different ways to solve this problem.