13 is a whole number, integer, natural number and rational number. Rational number because it can be written as a fraction like 13/1. It is a whole number because it doesn't have any decimals. It is an integer because an integer is a positive or negative whole number and it is a natural number because a natural number is any positive number greater than 0.
The greatest common factor of sets of mathematical expression is that which can divide both and give the least answer. For the first set, the GCF is equal to 4ab^2. For the second set of mathematical expressions, the GCF is 4ab^2.