After the kind and grade of food have been decided on, it is next necessary to determine the definite amount to buy, which depends primarily on such factors as the following: The amount allowed for one person (this amount is the basis of good buying and if properly estimated insures enough food for all and eliminates to a great degree the problem of left-over food [see Table XXII]); the number to be fed; the number of times the food is to be served; the keeping qualities of the food (the amount bought should be small enough to prevent depreciation); the available storage facilities; the amount of money available to invest (interest on the money invested in food should be added to the cost of the food): the terms of contract: the relative ad vantages of buying in large quantities; the season of the year (it is best to buy large amounts of food for storage when the new crops come in; this is especially true of dried fruits and many grain products, which come on the market but once a year); the cost.