How to find sum of columns in datagridview in C#

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C#

I want the answer like this:

Column A	Column B	Column C
12.02	         10.00	         22.02
32.02            10.00           42.02
52.02

What I have tried:

private void DgView_CellValidated(object sender, DataGridViewCellEventArgs e)
        {
         if (DgView.CurrentCell.ColumnIndex == 0)
                {
                    DgView.Rows[DgView.CurrentCell.RowIndex].Cells[1].Value =                         cfun.convertdecimal(DgView.Rows[DgView.CurrentCell.RowIndex].Cells[0].Value.ToString())  + cfun.convertdecimal(txtValue.Text.ToString());
                }
}
 private void DgView_RowValidated(object sender, DataGridViewCellEventArgs e)
        {
            decimal sum = 0;

            for (decimal i = 0; i < DgView.Rows.Count+1; ++i)
            {
                sum = cfun.convertdecimal(DgView.Rows[DgView.CurrentCell.RowIndex].Cells[1].Value.ToString())
                     + cfun.convertdecimal(DgView.Rows[DgView.CurrentCell.RowIndex].Cells[2].Value.ToString());
            }
            DgView.Rows[DgASideView.CurrentCell.RowIndex].Cells[0].Value = sum.ToString();
        }

when i try this code 1st row 1st column is changing.want to display the sum in 2nd row 1st column and continuously