How to change the total amount inserted more than 1 product

Question

Hi

 

I want to create a windows form there is the field

Product Name       textbox

Product Price        textbox

Quantity                textbox

Total Amount        textbox

 

if the product price is 24 and when I insert the Quantity 1 the total amount auto come in the

total amount textbox

 

and if I enter more than 1 quantity base price is 24 but need to update the total amount as per the quantity.

 

please help me with this how I can do this