I am building a gradebook with limited knowledge of Excel. To get a weighted
percentage, I came up with this

=(I4/I$3)*0.05+(Y4/Y$3)*0.2+(AJ4/AJ$3)*0.2+(AU4/AU$3)*0.25+(AW4/AW$3)*0.05+(AY4/AY$3)*0.1+(BA4/BA$3)*0.15

However, the last few have zeros in the denominator (for example: BA3) as
there is no grade for them yet (exams, final projects, etc). How do I
exclude these from the formula to get a grade in the meantime until there is
a grade for the last few?

Thank You,
Austin