具体是这样的:

invoke the web service of http://samples.gotdotnet.com/quickstart/aspplus/samples/services/MathService/CS/MathService.asmx?WSDL

which service privided the math mothd such as add/sub/mulite/div.

I invoke the mothd in the win ce with compact framework,

ye,the result is out at faniliy.I am happy now.

some source followed :

switch (comboBox1.SelectedItem.ToString())
{
case "+":
textBox3.Text
= MathService.Add(Single.Parse(textBox1.Text),Single.Parse(textBox2.Text)).ToString();
break;
case "-":
textBox2.Text
= MathService.Subtract(Single.Parse(textBox1.Text),Single.Parse(textBox2.Text)).ToString();
break;
case "*":
textBox2.Text
= MathService.Multiply(Single.Parse(textBox1.Text),Single.Parse(textBox2.Text)).ToString();
break;
case "/":
textBox2.Text
= MathService.Divide(Single.Parse(textBox1.Text),Single.Parse(textBox2.Text)).ToString();
break;

}