Find the number of positive integers that satisfy the following conditions: * Each digit is a 1 or a 2 or a 3 * The sum of the digits is 10
There are 15 positive integers that satisfy the given conditions. They are: 111, 112, 113, 121, 122, 123, 131, 132, 133, 211, 212, 213, 221, 222, 223.
