How to do Sum operation on multiple rows specific cells of Datagridview in windowsforms using c#?

It is usually best to do operations on the underlying data structure, such as a DataTable.

1. Add the following member variable to your class.

private DataTable dtRecord;

2. I had to add init code somewhere

private void Form1_Load(object sender, EventArgs e)
{
    dtRecord = new DataTable("Record");

    dtRecord.Columns.Add("Id", typeof(System.Int32));
    dtRecord.Columns.Add("Name", typeof(System.String));
    dtRecord.Columns.Add("Balance", typeof(System.String));

    dtRecord.Rows.Add(1, "Sai", "10000Cr");
    dtRecord.Rows.Add(2, "Ram", "3000Dr");
    dtRecord.Rows.Add(3, "Anu", "5000Cr");
    dtRecord.Rows.Add(4, "Swathi", "4000Dr");

    bindingSource1.DataSource = dtRecord.DefaultView;
    dataGridView1.DataSource = bindingSource1;

    CalculateSum();
}

3. You can use for example the event CellEndEdit

private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
    bindingSource1.EndEdit();   // Applies the changes to the data table
    if (e.ColumnIndex == 2)
    {
        CalculateSum();
    }
}

4. The method CalculateSum as the very simplest implementation

private void CalculateSum()
{
    double sum = 0.0;
    // Regular expression with named groups makes it easy to extract the data
    Regex balanceExpression = new Regex(@"(?<value>\d+)(?<type>cr|dr)", RegexOptions.IgnoreCase);
    foreach (DataRow dr in dtRecord.Rows)
    {
        string balance = dr["Balance"].ToString();
        Match m = balanceExpression.Match(balance);
        if (m.Success)
        {
            if (m.Groups["type"].Value.ToUpper() == "CR")
                sum += double.Parse(m.Groups["value"].Value);
            else
                sum -= double.Parse(m.Groups["value"].Value);
        }
    }

    textBox1.Text = sum.ToString("N2");
}
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Of course there are plenty of other ways to do the same thing, for example using LINQ for calculating the sum.