Let's try one more example. Find the greatest common factor of 11, 24, and 30. We'll start the same way that we did in the previous example, by finding the prime factorization for each number. 11 is prime, so the prime factorization of 11 is itself. It's 11. Let's look at the prime factorization of 24. 24 is even, so 2 is a factor, and 24 divided by 2 is 12. 12 divided by 2 is 6. 6 divided by 2 is 3, and 3 is prime. So the prime factorization of 24 is 2 times 2 times 2 times 3. Now for the prime factorization of 30, we again will start by dividing 30 by 2. 30 divided by 2 is 15. 15 is not an even number, so 2 is not a factor of 15 but 3 is. 15 divided by 3 is 5. So the prime factorization of 30 is 2 times 3 times 5. Again, we're going to create a table, and this time we'll need four columns: a column for two, a column for three, a column for 5, and a column for 11. Now, let's write the prime factorization for each of our numbers in this table, starting with 11. Well, 11 is prime, so 2 is not a factor of 11, so we can put a dash there or just leave that blank. 3 is also not a factor of 11. We can leave that blank or put a dash there. 5 is not a factor of 11, but 11 is a factor of 11. Again, 11 is prime, so the prime factorization of 11 is itself. Let's go to our next number, which is 24. 24 contains three factors of 2. Put those three factors of 2 in the two column. One factor of 3, which goes in the three column. There is no factor of 5 in 24, so we'll leave it blank or put a dash there. And no factor of 11 in 24, so, we'll put a dash there as well. Finally, we have the number 30. 30 does have a factor of 2. Just one, so we'll put one 2 in the two column. It has one factor of 3, so one 3 goes in the three column. And one factor of 5. So one 5 goes in the five column. 11 is not a factor of 30, so we would leave that blank or put a dash in that eleven column. Now remember, once we have this table complete, the greatest common factor is found by circling the least products in each column that does not have a blank. Well, we put these dashes here to help remind us that if there's a dash in a column, that means that factor is not a common factor to all three numbers. 2 is not a common factor to all three numbers because it's not a factor of 11. Same goes for 3. 5 is not a factor of 11 or 24. And 11 is only a factor of 11, not of 24 and 30. So what is the greatest common factor of these three numbers? It appears they don't have any factors in common. But remember that 1 is a factor of each of these numbers, so 1 is the greatest common factor. So we can say that the greatest common factor of 11, 24, and 30 is 1.