How to sum the rows in datagrid view and display in next row

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C#

Hi Frds,

Id Item Qty
1 AAAA 200
1 BBBB 300
Total 500
2 CCCC 100
2 DDDD 200
Total 300
I want to sum the same ID qty and display in next row. I don't Know how to proceed this. Anyone guide me.Thanks in Advance

What I have tried:

Decimal sum1 = 0;
int i;
for (i = 0; i < dataGridView1.Rows.Count; i++)
{
sum1 += Convert.ToDecimal(dataGridView1.Rows[i].Cells[2].Value);

}

dataGridView1[2, dataGridView1.Rows.Count - 1].Value = sum1.ToString();