Calculated Column

I have a dataGridView That has 2 columns:
PartCost and partQuantity
I would like to have a calculated column that shows the totla cost by multiplying the first 2 columns. What is the best way to do this so this calculated column is filled when the rest of the table is filled?
Thanks

Use a datatable, add 3 columns to it. The 1st column is for price, the 2nd for qty, and the 3rd for total cost. Set the 3rd column's expression = column0 * column1 and then bind that table to your datagridview.