Calculate total value of textboxes
<p>I have 8 textboxes that only accept integers. How to calculate the total of value entered by users in each textbox and the result will be showed as a label. After user click on submit button, the the value of the label(result of numbers) will be stored in db. Anyone knows? Thank you. Looking forward to hear from u guys. 
I got this error : <strong>Input string was not in a correct format.</strong> 
At this line: </p>

<pre><code>int total = 0;
total = int.Parse(TextBox2.Text) + int.Parse(TextBox4.Text) + int.Parse(TextBox6.Text) + int.Parse(TextBox8.Text) + int.Parse(TextBox10.Text) + int.Parse(TextBox12.Text) + int.Parse(TextBox14.Text) + int.Parse(TextBox16.Text);    
Label1.Text = total.ToString(); 
</code></pre>
