Try this now. Before try this remove your blur event from html.I hope this will help you.
$(document).ready(function () {
$("input[type=text]").blur(function () {
var portion = $(this).val();
var price = $(this).parent().parent().find(".price p").text();
if(isNaN(portion)==false)
{
var tot = portion * price;
$(this).parent().parent().find(".total p input").val(tot);
}
else
{
$(this).parent().parent().find(".total p input").val(0);
}
});
});
Demo here