displaying a product generated from one of two input-methods, cost per length, or per unit

Someone might generate one of two 'products/multiplications' - price depending on unit or, length - the data for which are collected under separate columns (a1,b1 or c1d1) and I would then like to display the product of either, in a single column - I'm thinking, there's a rule/precedence, if there's an answer in one, the answer is in red, if the product comes from the second column, the answer is in green - is conditional formatting ; but how do ask a cell to choose between boxes, based on two blank cells out of four.. messy to just ignore zeroes.

Is there a better way?

Hi
question is not clear, please post an example.

I'll do a graphic, cheers
excel product-select.JPG

maybe

It seems to want to '*' the condition -- =IF(AND(E17=0,F17=0),H17*I17,E17*F17)

I was missing the comma after the brackets : works very happily

exactly as you surmised,

gosh

Alright, it's making sense. Thanks