Cara buat Converter MM ke INC

<script type="text/javascript">function changeButton2716(){document.getElementById('convertButton2716').style.backgroundImage="url(http://www.metric-conversions.org/img/calcButton.jpg)";}function changeBack2716(){document.getElementById('convertButton2716').style.backgroundImage="none";}function convert2716(){var arguement=(document.inputForm2716.arguement.value-0);arguement=(arguement-0);arguement=(arguement*0.001);arguement=(arguement/0.0254);arguement=(arguement+0);arguement= Math.round(arguement*1000)/1000;document.inputForm2716.result.value= arguement+' "';}</script><form name="inputForm2716" id="inputForm2716"><div style="background-image:url(http://www.metric-conversions.org/img/calcTool.jpg);background-repeat:no-repeat;background-color:#000000;height:180px;width:230px;"><a href="#" style="position:relative;display:block;width:240px;padding:8px 0 0 0;margin:0 0 0 0;font-family:Arial, Helvetica, sans-serif;font-size:12px;font-weight:bold;text-align:center;color:#FFFFFF;text-decoration:none;">conversions mm to inches</a><input type="text" name="arguement" id="arguement" style="background-image:url(http://www.metric-conversions.org/img/calcIP.jpg);width:207px;height:32px;font-family:Arial, Helvetica, sans-serif;font-size:24px;font-weight:bold;border:0px;position:relative;top:20px; left:21px; line-height: 34px;padding:0 0 0 0;margin:0 0 0 0;" value="Enter value here" onfocus="javascript:this.value='';" /><div id="convertButton2716" style="position:relative;display:block;height:30px;width:105px;top:26px;left:124px;padding:0 0 0 0;margin:0 0 0 0;border:0px;z-index:2;cursor:pointer;" onmouseover="javascript:changeButton2716();" onmouseout="javascript:changeBack2716();" onclick="javascript:convert2716();"></div><input id="result" type="text" name="arg" style="background-image:url(http://www.metric-conversions.org/img/calcIP.jpg);width:207px;height:32px;font-family:Arial, Helvetica, sans-serif;font-size:24px;font-weight:bold;border:0px;position:relative;top:32px; left:21px; line-height: 34px;padding:0 0 0 0;margin:0 0 0 0;" value="" readonly="readonly" /><span style="position:relative;display:block;top:44px;left:4px;width:230px;padding:0 0 0 0;margin:0 0 0 0;font-family:Arial, Helvetica, sans-serif;font-size:12px;font-weight:bold;text-align:center;color:#FFFFFF;text-decoration:none;">provided by metric-conversions</span></div></form>