With cost in A1 and quantity in B1, put this formula in C1:

=IF(B1="","",B1*A1)

Will remain empty until a value is put in B1.

Hope this helps.

Pete

On Nov 28, 8:18 am, Dave wrote:
I would like to know how to mulitply a cell up when you input a quantiy, i.e
in one cell I would have a cost and another cell I would have quantiy. I need
it so when I put in a quantiy it would then multiply this by what I have
entered. Hope this makes sense.
Dave