What is the greatest common factor of 20, 30, 80 and 50?

To find the greatest common factor (GCF) of 20, 30, 80, and 50, follow these steps:

1. First, list the prime factors of each number:

   • 20 = 2 * 2 * 5
   • 30 = 2 * 3 * 5
   • 80 = 2 * 2 * 2 * 2 * 5
   • 50 = 2 * 5 * 5

2. Then, identify the common factors:

   • The common factors are 2 and 5.

3. The greatest common factor is the product of the lowest power of the common factors:

   • The lowest power of 2 that appears in all the factorizations is 2^1.
   • The lowest power of 5 that appears in all the factorizations is 5^1.

4. Multiply these together to get the GCF:

   • GCF = 2^1 * 5^1 = 2 * 5 = 10

So, the greatest common factor of 20, 30, 80, and 50 is 10.