For this problem solved by using RowDataBound Event of gridView
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="true" OnRowDataBound="CustomersGridView_RowDataBound">
</asp:GridView>
c# page code
DataTable dt = new DataTable();
protected void Page_Load(object sender, EventArgs e)
{
dt.Columns.Add("amt", typeof(Int32));
dt.Columns.Add("pamt", typeof(Int32));
dt.Columns.Add("damt", typeof(Int32));
DataRow dr=dt.NewRow();
dr[0] = 200;
dt.Rows.Add(dr);
DataRow dr1 = dt.NewRow();
dr1[0] = 400;
dt.Rows.Add(dr1);
GridView1.DataSource = dt;
GridView1.DataBind();
}
protected void CustomersGridView_RowDataBound(Object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
e.Row.Cells[1].Text =Convert.ToString(Convert.ToInt32(e.Row.Cells[0].Text)*15/100);
e.Row.Cells[2].Text = Convert.ToString(Convert.ToInt32(e.Row.Cells[1].Text) * 15);
}
}