Formula for grand total

I WANT THE GRAND TOTAL IF TOTAL(="")OR(<>"")IT MUST SHOW ME THE GRAND TOTAL
WITH THE MULTIPLICATION OF PRICE COLUMN AND QTY COLUMN


S.No Particulars P/P/U Qty Total
700.00 8.00
1 tables 3,500.00 3.00 10,500.00
3,600.00 5.00






GRAND TOTAL( )





HOPE FOR YOUR SOON REPLY

REGARDS,

MAKHDOOM