What is the sum of all the common factors of 18 and 63?

Sure, let's find the common factors of 18 and 63 step by step.

Step 1: Find the factors of 18 The factors of 18 are: 1, 2, 3, 6, 9, 18

Step 2: Find the factors of 63 The factors of 63 are: 1, 3, 7, 9, 21, 63

Step 3: Identify the common factors The common factors of 18 and 63 are: 1, 3, 9

Step 4: Sum the common factors The sum of 1, 3, and 9 is 13.

So, the sum of all the common factors of 18 and 63 is 13.