jquery - I want to do calculation inbetween column table and the values should be stored in Final Amount column -

kindly me new this. want calculation (selected value divisible 1000) , multiple amount , should stored in 5th column. ie product1 = (100 / 1000) * 100 = 10

here code:

<table border="1"> <tbody>     <tr>         <td width="334">s.no.</td>         <td width="334">product name</td>         <td width="334">amount</td>         <td width="334">grams/kg</td>         <td width="334">final amount</td>     </tr>     <tr align="center">         <td>1</td>         <td>product1</td>         <td>100</td>         <td>             <select id="grams">                 <option value=""></option>                 <option value="100">100g</option>                 <option value="250">250g</option>                 <option value="500">500g</option>             </select>         </td>         <td>i want calculation (selectedvalue / 1000) * amount, amount want reflect here</td>     </tr>     <tr align="center">         <td>2</td>         <td>product2</td>         <td>200</td>         <td>             <select id="grams">                 <option value=""></option>                 <option value="100">100g</option>                 <option value="250">250g</option>                 <option value="500">500g</option>             </select>         </td>         <td>i want calculation (selectvalue / 1000) * amount, amount want reflect here</td>     </tr> </tbody> 

this might understand how format table values

$(function(){   $('select').change(function(){         var td_id = 'row'+$(this).attr('id');         var val = $(this).val();         var amount = $('.'+td_id+'-amount').html();         $('#'+td_id).html(val/1000*amount);   }); }); 

in example have add ids , classes. see fiddle

(i thought wanted have more 2 rows. other answers may more easy use in case)