[nabi]

hi

i was wondering if anyone knew how to do calculations in javascript?
i want to use this to design my first shopping cart.

e.g. when a user clicks on a checkbox, it will automatically recognise that the item is e.g. $30 and then if/when a user clicks on another item which is e.g. $50, the script will add up the $30 + $50 and send it to the url or somewhere else if possible.

i am a beginner in programming so please can you help me with this as i would be very grateful, if you cant help me solve this problem then can you please tell me where i can find a free, good and easy to program paypal shopping cart?