I have the following equation...

Frost Time = ((-24.5 x ((0.667 x (wind x 8/5)) +4.8)) + 2111) x (-4.8 - ((temperature -32) x 5/9))^-1.668

wind = cell x4
temperature = cell y4

I came up with the following equation...

SUM(-24.5*(SUM(0.667*(X$4*(8/5)))+4.8),2111) *sum ((-4.8,-((Y$3-32)*(5/9)))^-1.668)

but I keep getting the error #NUM!

Can anyone point out my error?

Thanks!

Jeff