Permitir numeros, bloquear letras

[Peterpay]

private void dataGridView1_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
{
((DataGridViewTextBoxEditingControl)sender).KeyPre ss += new KeyPressEventHandler(Form1_KeyPress);
}

void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
if(e.KeyChar... comparasiones contra numeros pero en falso o verdadero depende tu logica)
e.Handled=true;
}

saludos
peter