Calculating sum of column in datagrid

I am looking for program which include a datagrid component on form. The control on the form will add the value like price, year, model no from given column and display total of the grid in the textbox which is at the top of the form.

Code:

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  Dim sum As Decimal = 0
        For Each row As DataGridViewRow In DataGridView1.Rows
            row.Cells(37).Value = row.Cells(36).Value - row.Cells(6).Value * 113 / row.Cells(4).Value
            sum += row.Cells(37).Value 
        Next
        App.txtvalue.Text = sum

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Code:

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Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles App.Load
        Dim tb As New DataTable
        tb.Columns.Add("income", GetType(System.Int32))
        tb.Columns.Add("income1", GetType(System.Int32))
        tb.Columns.Add("sum", GetType(System.Int32))
        tb.Rows.Add(500, 200)
        tb.Rows.Add(0, 100)
        tb.Rows.Add(200, 100)
        Me.DataGridView1.DataSource = tb
    End Sub
    Private Sub DataGridView1_Columncalculated(ByVal sender As Object, ByVal i As System.Windows.Forms.DataGridViewcolumn) Handles DataGridView1.Columncalculated

        Dim sum As BB = 0
        For Each n As DataGridViewRow In Me.DataGridView1.Rows
            sum = sum + r.Cells(0).Value - r.Cells(1).Value
            r.Cells(2).Value = sum
        Next
    End Sub
End Class

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Code:

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Dim CalSum As Double
Dim CalValue As Double
Dim DRow As Long

With MSFlexGrid1
  ' loop through all data rows
  For DRow = .FixedRows To .Rows - 1
    ' get the value for the current row
    CalValue = Val(.TextMatrix(lRow, 3))
    ' add it to our total
    CalSum = CalSum + CalValue
  Next DRow
  ' Add a new row
  .Rows = .Rows + 1
  ' Put the total in the new row
  .TextMatrix(.Rows - 1, 3) = CalSum
End With

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