I use drupal 7 an I want to add very simple jquery code to only one page on my site. 

     $('#var1').on('keypress keydown keyup', function(){
       $(this).val($(this).val().replace(/([^\d]+)/, '')); 
    });
     $('form').submit(


     function (e) {
    e.preventDefault();
     var xyz = parseInt($('#var1').val());
    $('#result').text("Result is " + ((xyz / 1.25)*30) + " days");
     });

     <form>
    <input type="text" id="var1" />
    <input type="submit" value="=" />
     </form>
     <span id="result"></span>

The problem is that pressing submit button allways reloads wlole page which I do not need. How to prevent this? Thank you.
I need it to work as smooth as this without reloading http://jsfiddle.net/eWXUT/3/

EDIT: I put the code on livesite but it is not working http://www.vypadavanie.net/ako-rychlo-rastu-vlasy?