Sort of a novice to excel here...

I'm having a huge amount of difficulty getting excel to understand what I'd like. Essentially, I want to take data I input into three separate columns and have it inputted into an equation. The equation is 0.5(4/3*(pi*a*b*c)). Four-thirds multiplied by pi multiplied by a multiplied by b multiplied by c, all divided by 2.

a, b, and c are essentially values from columns 1,2, and 3.

Each time I input = followed by my equation in the cell I want it to appear (including selecting the appropriate cells from which to import the values of a,b, and c), an error message pops up. If I need to pare down the equation more simple to allow for this to work, I can.

Any help is appreciated. Thanks!