title: JSTL cannot parse a double variable multiplied by an integer variable?
body: <p>If I set two variables in my controller:</p>
  
  <pre><code>double doubleAmount = 18.0;
  int integerAmount = 2;
  </code></pre>
  
  <p>And then try to multiply them in my JSTL code:</p>
  
  <pre><code>&lt;c:set var="result" value="${doubleAmount} * ${integerAmount}"/&gt;
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>javax.servlet.ServletException: 
  javax.servlet.jsp.JspException: 
  In &amp;lt;formatNumber&amp;gt;, 
  value attribute can not be parsed into java.lang.Number: 
  "18.0 * 2"
  </code></pre>
  
  <p>How do I perform this operation in my JSTL code?</p>