how to calculate percentage in repirt

[abieyuwae]

I'm trying to calculate percentage in a report.
example:
total hrs: =sum([hrs])
percent: =[total hrs]/[grand total]

grand total:=([hrs])

my total hours is fine...but the percentage gives me a bunch of parameter values i never specified and it doesn't show the percentage, only the total hrs shows.
please could anybody help ...as any suggestion is welcome.
thank you.

 

[eason]

Try this,

([total hr]*100)/[Grand hr]-100