>The Grid is not editable...

Ok, then put this in the textbox.Init()

local lnRec, lnWA
lnWA = select()
select MyTable
lnRec = recno()

sum quant * price to lnTotal

go (lnRec)
select (lnWA)

This.Value = lnTotal

Make sure to use your table's alias instead of MyTable.