Private Sub txtBox_TextChanged(sender As Object, e As EventArgs) Handles txtBox.TextChanged
        dtgw.ClearSelection()
        Dim IndexFilaEncontrada As Integer = Nothing
        For Indice As Integer = 0 To dtgw.Rows.Count - 1
            dtgw.Rows(Indice).Visible = True
        Next
 
        For Each Column As DataGridViewColumn In dtgw.Columns
            For Each row As DataGridViewRow In dtgw.Rows
                Try
                    If txtBox.Text.ToString.ToLower.Equals(row.Cells(Column.Index).Value.ToString.ToLower) Then
                        IndexFilaEncontrada = CInt(row.Index)
                        For Indice As Integer = 0 To dtgw.Rows.Count - 1
                            If Not Indice = IndexFilaEncontrada Then
                                dtgw.Rows(Indice).Visible = False
                            End If
                        Next
                    End If
                Catch ex As Exception
                End Try
            Next
        Next
 
    End Sub

i=CInt(val("10 * 25"))

Option Strict Off
Module Module1
 
    Sub Main()
        Dim Valor As String = Val("10 * 25")
        Console.WriteLine(Valor)
        Console.ReadLine()
    End Sub
 
End Module
 

        Dim Valor As String = "10 * 25"
        Dim t() As String
        t = Valor.Split({" "}, StringSplitOptions.RemoveEmptyEntries)
         If Char.IsNumber(t(0)) And Char.IsNumber(t(2)) Then
        Console.WriteLine(t(0) * t(2))
        End If
        Console.ReadLine()
 

  Dim Valor As String = "10 - 25"
        Dim t() As String
        t = Valor.Split({" "}, StringSplitOptions.RemoveEmptyEntries)
            If Char.IsNumber(t(0)) And Char.IsNumber(t(2)) Then
            Select Case t(1)
                Case "*" : Console.WriteLine(t(0) * t(2))
                Case "/" : Console.WriteLine(t(0) / t(2))
                Case "+" : Console.WriteLine(CInt(t(0)) + CInt(t(2)))
                Case "-" : Console.WriteLine(t(0) - t(2))
            End Select
        End If
        Console.ReadLine()

Public Class Form1
    Dim WithEvents dtgw As New DataGridView
    Dim WithEvents bSearch As New Button
    Dim WithEvents txtBox As New TextBox
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
 
        With Me
            .Controls.AddRange({dtgw, bSearch, txtBox})
            .Width = 510
 
            With .dtgw
                .Size = New Size(500, 150)
                .ColumnCount = 3
                .Columns.Item(0).Name = "Nombre"
                .Columns.Item(1).Name = "Apellido"
                .Columns.Item(2).Name = "País"
            End With
 
            bSearch.Location = New Point(155, 160)
            bSearch.Text = "Buscar"
            txtBox.Location = New Point(50, 160)
            txtBox.Width = 100
 
            .dtgw.Rows.Add("Julio", "Hernández", "Puerto Rico")
            .dtgw.Rows.Add("Alicia", "Casanova", "España")
            .dtgw.Rows.Add("Manuel", "Pérez", "México")
 
 
        End With
    End Sub
 
    Private Sub bSearch_Click(sender As Object, e As EventArgs) Handles bSearch.Click
        dtgw.ClearSelection()
        For Each Column As DataGridViewColumn In dtgw.Columns
            For Each row As DataGridViewRow In dtgw.Rows
                Try
                    If txtBox.Text.ToString.ToLower.Equals(row.Cells(Column.Index).Value.ToString.ToLower) Then
                        row.Cells(Column.Index).Selected = True
                    End If
                Catch ex As Exception
                End Try
            Next
        Next
    End Sub
End Class

 With .dtgw
                .Size = New Size(500, 150)
                 .AllowUserToAddRows = False  '<-------
                .ColumnCount = 3
                .Columns.Item(0).Name = "Nombre"
                .Columns.Item(1).Name = "Apellido"
                .Columns.Item(2).Name = "País"
            End With
 
 
.....
 
    Private Sub bSearch_Click(sender As Object, e As EventArgs) Handles bSearch.Click
        dtgw.ClearSelection()
        For Each Column As DataGridViewColumn In dtgw.Columns
            For Each row As DataGridViewRow In dtgw.Rows
                If txtBox.Text.ToString.ToLower.Equals(row.Cells(Column.Index).Value.ToString.ToLower) Then
                    row.Cells(Column.Index).Selected = True
                End If
            Next
        Next
    End Sub
 

    Private Sub dtgw_RowPrePaint(sender As Object, e As DataGridViewRowPrePaintEventArgs) Handles dtgw.RowPrePaint
       e.PaintHeader(DataGridViewPaintParts.Background _
                      Or DataGridViewPaintParts.Border _
                      Or DataGridViewPaintParts.Focus _
                      Or DataGridViewPaintParts.SelectionBackground _
                      Or DataGridViewPaintParts.ContentForeground)
        e.Handled = True
    End Sub
    Private Sub dtgw_CellFormatting(sender As Object, e As DataGridViewCellFormattingEventArgs) Handles dtgw.CellFormatting
        'Texto de la cabecera de la fila
        'dtgw.Rows(e.RowIndex).HeaderCell.Value = "Fila-" & e.RowIndex.ToString()
    End Sub