How do I estimate the size of the Megalodon Shark by the tooth?

You can estimate the size of the Megalodon tooth if you have a primary tooth ( one of the top teeth in the jaw which is for the most part symmetrical) It is about 1/8 of an inch for every foot. So to determine the size of a shark with a 7-inch tooth: There are eight 1/8’s of an inch in an inch. 8 X 7″ inches is 56 ft