What is the sum of all the common factors of 99 and 33?
To find the common factors of 99 and 33, we first need to find the factors of each number. The factors of 99 are 1, 3, 9, 11, 33, and 99. The factors of 33 are 1, 3, 11, and 33. The common factors are 1, 3, and 11. Adding these common factors together gives us 1 + 3 + 11 = 15. Therefore, the sum of all the common factors of 99 and 33 is 15.