After I explain the procedure in full detail, you'll be able to generate
your own work. Here it is.
To find the greatest common factor of two numbers:
1). List all of the factors of the first number.
2). List all of the factors of the second number.
3). Scan both lists, and find factors that are on BOTH lists.
These are the COMMON factors. Write them down in a short list.
4). Scan the short list. Find the biggest number on it.
That's the Greatest Common Factor.
OK, I'll go through the first one in your picture . . . 24 and 42 :
1). Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
2). Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42
3). Short list: 1, 2, 3, 6
4). Biggest number on the short list: 6
