For the sake of argument, in this case let’s take Fox’s upper estimate of $120 Billion/year. That’s too big a number for any of us to relate to or understand, so Step 1 is to convert it into ounces or joints of marijuana. The price of an ounce varies based on where you are, whether you buy in bulk, and what grade you purchase. But $120/ounce isn’t a bad estimate for a national average in any case, and here it makes the math easy so let’s use it. If marijuana costs $120/ounce, Americans would have to purchase 1 billion ounces a year to reach the $120 Billion dollar estimate. Already you will be suspicious of Fox’s market number because this works out to over 3 ounces per American (1 billion ounces divided by slightly over 300 million people), assuming that everyone uses marijuana, including newborns, people in comas and emphysema patients.