Doxorubicin's calculations are right if your GPA is not weighted... If it is weighted, divide your GPA by the weight.
For example, my school works on the 100 scale, but advanced courses are weighted by 10%. I received a 99 in my spanish course for the year, but I really received a 90 due to the 1.1 I had to divide...
99 ÷ 1.1 = 90