Ignore blanks for weighted grades

Hello,

I am relatively new to several functions in Excel and need some guidance on how to create a formula to calculate my students' weighted average even when some of the cells are blank (i.e. some grades are missing). I am currently using an old gradebook I created but it doesn't show actual grades until I populate all cells. The formula I have for the section in the picture below is:

=(C6*100/$C$5)*$C$4+(D6*100/$D$5)*$D$4+(E6*100/$E$5)*$E$4+(F6*100/$F$5)*$F$4+(G6*100/$G$5)*$G$4+(H6*100/$H$5)*$H$4+(I6*100/$I$5)*$I$4+(J6*100/$J$5)*$J$4+(K6*100/$K$5)*$K$4+(L6*100/$L$5)*$L$4

My goal is to use a function to calculate real grades even when not all cells contain data. You will notice in the picture that I have different weights and also not all projects are calculated out of 100. Any chance I can use a function to do what I want?

Thanks in advance for any help you can provide!

Projects.JPG

Please post a sample worbook, not a picture.

Originally Posted by MSExcelLnr

=(C6*100/$C$5)*$C$4+(D6*100/$D$5)*$D$4+(E6*100/$E$5)*$E$4+(F6*100/$F$5)*$F$4+(G6*100/$G$5)*$G$4+(H6*100/$H$5)*$H$4+(I6*100/$I$5)*$I$4+(J6*100/$J$5)*$J$4+(K6*100/$K$5)*$K$4+(L6*100/$L$5)*$L$4

You could simplify that formula to this:

=SUMPRODUCT(C6:L6/C$5:L$5,C$4:L$4)*100

....but what results do you expect when some cells are not populated - can you give an example for row 6?

OK, just for the projects part you could try this formula in M6 copied down

=IFERROR(SUMPRODUCT(C6:L6/C$5:L$5,C$4:L$4)*100*M$5/SUMIF(C6:L6,"<>",C$4:L$4),0)

That will leave the results unchanged when all cells are populated, but if some projects are blank it will just calculate based on results so far, so if you only have 1 project completed but get 100 out of 100 then your score so far will be the maximum 15.00

Is that what you need?