Select your other 2 apps below to get all 4 apps running in minutes:
 
1) Select  1.additional $50-app:  

2) Select  2.additional $50-app:  

3) Enter your 14-digit Calculator ID
 (
How to find this ID)

                          
(Length=14, don't enter '#' , '-' or spaces. 
 Don't confuse '8' and 'B', '0' and 'D'.  Not
 case sensitive.)

Immediately after the Paypal checkout, an email will be sent to you containing your activation keys and installation instructions. You may read the instructions here as well: http://www.ti89.com/thankyou.htm