4 * 2 *x*y = exp(log( 4 )+log( 2 )+log(x)+log(y))

<?xml version='1.0'?>
<?xml-stylesheet type="text/xsl" href="mul.xsl"?>
<root>
  <Amount> 4 </Amount>
  <Amount> 2 </Amount>
</root>

<?xml version="1.0" ?>

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:math="urn:math"
 xmlns:msxsl="urn:schemas-microsoft-com:xslt">

<msxsl:script implements-prefix="math" language="JavaScript">
<![CDATA[
    function mul(nodelist)
    {
 var result =  1 ;
 for (var i= 0 ; i<nodelist.length;i++)
 {
  result *= nodelist.nextNode().text;
 }
 return result;
    }

]]>
</msxsl:script>

<xsl:template match="/">
  <xsl:value-of select="math:mul(//Amount)" />
</xsl:template>

</xsl:stylesheet>