LG

You put in the Pre Post prices, from what I gathered here on this post, either one's own ratings, or the Pre Post from racing pages.
That's in Column C
'
The Openers, where ever one gets their openers from, that goes in Column D
,

Put in all the runners for that race if you wish.
Then press the button that says "SORT"
It will simply sort the highest rated to the lowest and delete the blanks.

It's a very basic calculator according to the rules I found as written. They are not my rules or formula.

Once you have completed a race and have filed it, press the button that says, RESET, and ya good to go onto the next race.

The $100 in Cell F2, calculates if you want to "make 100" calculated from the Opening Price.
The RATE calculation is according to the pre-posts.
I don't keep stats, too many opinions on "official" bookies openers. So over time one gets a "feel" for it.

Hope that helps, ..