The second role of money is to provide a unit of account; that is, it is used to mea sure value in the economy. We measure the value of goods and services in terms of money, just as we measure weight in terms of pounds or distance in terms of miles. To see why this function is important, let's look again at a barter economy where money does not perform this function. If the economy has only three goods-say, peaches, economics lectures, and movies-then we need to know only three prices to tell us how to exchange one for another: the price of peaches in terms of economics lectures (that is, how many economics lectures you have to pay for a peach), the price of peaches in terms of movies, and the price of economics lectures in terms of movies. If there were Len goods, we would need to know 45 prices to exchange one good for another; with 100 goods, we would need 4,950 prices; and with 1,000 goods, 499,500 prices 2 Imagine how hard it would be in a barter economy to shop at a supermarket with 1,000 different items on its shelves, having to decide whether chicken or fish is a bet ter buy if the price of a pound of chicken were quoted as 4 pounds of butter and the price of a pound of fish as 8 pounds of tomatoes. To make it possible to compare prices, the tag on each item would have to list up to 999 different prices, and the time spent reading them would result in very high transaction costs. The solution to the problem is to introduce money into the economy and have all prices quoted in tetms of units of that money, enabling us to quote the price of economics