http://hiddenmysteries.net/geeklog/a...70512093125130
The Ahmes code

The mathematical system in ancient Egypt was application-oriented, devised -- complete with fractions -- to manage practical matters. Assem Deif sums up the old methods

If an ancient Egyptian wanted to divide a loaf of bread among a group of workers or figure out the manpower needed to achieve a certain task, he used addition and doubling instead of the four operations of addition, subtraction, multiplication, and division we use today. It was their script that compelled them to use these operations, since they could double any given number by simply drawing the same symbol next to it. For a similar reason they are only used with unit fractions -- those whose numerator is 1 -- when solving problems about ratios.