Excel Calculation Automation For Large Field of Unknown Amount of Cells

[Qpido]

Dear Members,

I am trying to get VB6 to calculate many cells according to the data that is on the same line.

http://img685.imageshack.us/img685/314/screen3bl.png

(a would be calculated with diameter, length and quantity.)

The numbers under length will be placed according to an array, this might change depending on the different input. How could I make it so that each next cell know which relevant lines to calculate with?

Thanks so much,

Jerome