一个onclick事件中，服务器是根据什么进行运算的？

这段代码怎么识别运算的阿?里面好像没有运算法则什么的,连sum也没有啊，onclick="Add"事件中我把Add改成kk，然后再改void kk(object sender,EventArgs e)发现程序也能运行，那服务器是根据什么进行运算的？<script runat="server" Language="C#">
  void Add(object sender,EventArgs e)
  {
     try
        {
          double d=Convert.ToDouble(tbxInput1.Text)+
                   Convert.ToDouble(tbxInput2.Text);
          lblAnswer.Text=d.ToString();
        }
     catch
        {
          lblAnswer.Text="An error occurred";
        }
  }
  void Subtract(object sender,EventArgs e)
  {
     try
        {
           double d=Convert.ToDouble(tbxInput1.Text)-
                    Convert.ToDouble(tbxInput2.Text);
           lblAnswer.Text=d.ToString();
        }
     catch
        {
          lblAnswer.Text="An error occurred";
        }
  }
  void Factor(object sender,EventArgs e)
  {
     try
        {
           double d=Convert.ToDouble(tbxInput1.Text)*
                    Convert.ToDouble(tbxInput2.Text);
           lblAnswer.Text=d.ToString();
        }
     catch
        {
          lblAnswer.Text="An error occurred";
        }
  }
void Ratio(object sender,EventArgs e)
  {
     try
        {
           double d=Convert.ToDouble(tbxInput1.Text)/
                    Convert.ToDouble(tbxInput2.Text);
           lblAnswer.Text=d.ToString();
        }
     catch
        {
          lblAnswer.Text="An error occurred";
        }
  }
</script>
<html>
<form runat="server">
<asp:textbox id="tbxInput1" runat="server"/>
<asp:button id="btnAdd" runat="server" text="+" onclick="Add"/>
<asp:button id="btnSubtract" runat="server" text="-" onclick="Subtract"/>
<br/>
<asp:textbox id="tbxInput2" runat="server"/>
<asp:button id="btnFactor" runat="server" text="X" Onclick="Factor"/>
<asp:button id="btnRatio" runat="server" text="/" Onclick="Ratio"/>
<br/>
<b>Answer=<asp:Label id="lblAnswer" runat="server"/></b>
</form>
</html>