Three persons own 51 quarts of rice, and have only two measures; one a 4-quart, the other a 7-quart measure. How shall they divide it into three equal parts?
Method. One-third of 51 is 17; so each must have 17 quarts. To measure 17 quarts fill the 7-quart measure twice and pour into some large vessel, making 14 quarts; then fill the 7-quart measure, draw off 4 quarts in the 4-quart measure, and then pour the remaining 3 quarts in the vessel containing the 14 quarts.