I'm really bad at JS, and I've been searching for this, but all I found was http://javascript.internet.com/forms/order-form.html

I need some sort of a order page.
A form, with only one field, where you type in a number.
Now when the number is typed, somewhere on the same page, without submiting you see for example, if the number typed was 7, apper in a text box or someething in bold "75$".
Like, the first item was "15$" and each additional only 10$
So for 6 you'd get "65$"

Can someone help me with this if it isn't to much work?

Thanks alot!