how can i make it work

What formula do you use to calculate student grades based on letter grades?

Or do you just take the average of number grades?

Either way, export and upload your aia if you want to see blocks.

You could also search the board for GPA

I have never seen a grade system where you use higher values for the equivalent code for worse grades.

Any way, this looks like a good place to use a descending if/then/elseif ladder with 12(?) steps.

If grade > 96 then set global equivalent to 1.0
Elseif grade > 93 then set global equivalent to 1.25
Elseif grade > 90 then set global equivalent to 1.50
Elseif ...

(Corrected numbers from your chart)

Use the blue mutator button on the if/then block to keep adding sockets.