Новенькая,
<HTML>
<head>
<script language="JavaScript">
function my() {
var s = parseFloat(document.getElementById("sistnalog").value);
var m = parseFloat(document.getElementById("viddeat").value);
var r = parseFloat(document.getElementById("denob").value);
var l = parseFloat(document.getElementById("chisl").value);
var v = parseFloat(document.getElementById("docum").value);
result=s*m*r*l*v;
alert(result);
}
</script>
</head>
<body>
<p><form name="ya">
<select id="sistnalog">
<option value="4000" selected>
<option value="3000" >
<option value="5000" >
</select>
<p><select id="viddeat" >
<option value="1.2" selected>
<option value="2.1" >
<option value="2.2" >
<option value="2.5" >
<option value="1.1" >
</select>
<p><select id="denob" >
<option value="1.05" selected>
<option value="1.2" >
<option value="1.6" >
<option value="2.3" >
<option value="3" >
</select>
<p><select id="chisl" >
<option value="1.1" selected>
<option value="1.4" >
<option value="1.8" >
<option value="2.9" >
<option value="4" >
</select>
<p><select id="docum" >
<option value="1.1" selected>
<option value="1.2" >
<option value="2" >
<option value="3" >
<option value="5" >
</select>
<P><INPUT TYPE="BUTTON" VALUE="рассчитать" onClick="my()">
</form>
</body>
</html>