From JustSell.com:
Have you ever wondered why hot dogs typically come 10 to the package, while the buns come in batches of eight?
While some suspect that the disparity is a marketing tool meant to increase sales, hot dog historians point to a time when customers purchased meat from a butcher and buns from a baker. Meat was sold by the pound, with the typical frank weighing one–tenth of a pound; 10 franks came in the pound package. But pan sizes dictated that buns be baked in multiples of four. (The eight–bun pan is still the most common
pan size.)
Enjoy the Fourth and eat a dog or two!