I want to create a form for a web page. When customers place a 4 digit number
in a box - the adjoing box will give them a response based on their input.
Example: Customer enters (first box either or choice) 1 or 2 items.
second box - post code (4 digits) customer enters 4 digits
Third box - shows $ amt based on customer choices of first two boxes.

I can not find this calc anywhere!!

Can you help?