Update price automatically when quantity changed on product page Magento

Question

I am looking to have the product price automatically updated based on the quantity the customer has chosen.

Currently when you choose a custom option in magento the

Answer 1

Use jquery::

HTML CODE::

Jquery Code::

var price=100;
$("#quantity").on("change",function(){
    quantity=$(this).val();
    total_price=price*quantity;
    $("#total_price").html(total_price);

})