One way to find the GCF of 70 and 147 is to compare the prime factorization of each number. To find the prime factorization, you can follow the instructions for each number here:
Here is the prime factorization of 70:
And this is the prime factorization of 147:
When you compare the prime factorization of these two numbers, you can see that there are matching prime factors. You can now find the Greatest Common Factor of 70 and 147 by multiplying all the matching prime factors to get a GCF of 70 and 147 as 49:
Thus, the GCF of 70 and 147 is: 49