I am postng this in the Formula section where it belongs - sorry about that

"Jules" wrote:

I used to know how to do this, and can't remember. I think it is a COUNTIF
function in the first cell, together with conditional formatting in the 2nd
cell, but I can't remember how to set it up.

cell A1: any text at all entered will cause cell A2: part number to be
visible.

cell A1: empty value in cell A2 remains hidden.