It's a fair bet that few bothered to conduct this exercise here, as a search for Harville would have easily unearthed some useful information.

Particularly this excellent free Place calculator:

http://us.geocities.com/possum_31415/place.htm

Anyone wishing to learn some Betfair skills might like to try Place Betting using this.

It should provide significantly more action than Wesmip's simple formula.

I note that Betfair finally allows you to resize your windows a bit so it might even be possible to view Win, place and Calculator windows concurrently on the 1 screen.