Find this application on Windows Phone Marketplace at this location: http://www.windowsphone.com/s?appid=59680235-b5e2-41a9-b2f5-49eebfc62301
If you want to play online this calculator right now, check this link. It is described all you want to know about Matrakci and Lattice multiplication as well.
During holidays I was working on a small Windows Phone app. The application simulates how people performed multiplication more than 500 years ago. Before 500 years, people didn’t have devices we have today, so it was pretty complicated to calculate how much is e.g. 2345*6542. Those days, one of the discovered devices was Napier Bones, which could perform multiplication of pretty big numbers (with 2 or more digits). The device uses very clever method for multiplication, discovered 50 years before Napier constructed his Abacus. A recent study of the book, “Support of arithmetic in propositions of all magnitudes” (org. “Umdet-ul Hisab”) revealed an unknown fact that Matrakci had invented this genuine multiplication method. Nasuh Maktrakci was 16th century Ottoman mathematician, teacher, historian, geographer, cartographer, swordmaster, and miniaturist of Bosniak origin.
Currently application is preparing for sumbiting to marketplace, but there is a web silvelright version of the application which you can taste now. Just go to http://datasoft.ba/demos/matrakci/Matrakci.aspx and taste this very clever method for multiplication.