on asp.net page
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" onclick="Button1_Click" />
________
code behind
protected void Button1_Click(object sender, EventArgs e)
{
string[] numberArray = TextBox1.Text.ToString().Split(',');
for(int i =0 ; i < numberArray.Length -1; i++)
{
// number compare logic here
}
}