what are the highest common factor of 75 and 100?

First, we factorize each number.150=(5^2)32 and 100=(2^2)*(5^2) then to calculate the highest common factor we take the common factors with the smallest powers. In this case (5^2) and 2. That means that the highest common factor of 150 and 100 is (5^2)2=252=50.