title: PI and e constants in C# Visual Studio
body: <p>I'm trying to build a calculator in Visual Studio, in C#, and I want to use these important mathematical constants. I declare them:</p>
  
  <pre><code>public constant double PI;
  public constant double e;
  </code></pre>
  
  <p>But it shows an error for these declarations:</p>
  
  <blockquote>
    <p>A const field requires a value to be provided.</p>
  </blockquote>
  
  <p>What should I do, guys?</p>