So far, the more advanced calculators that have been offered at the App Store have been for engineers (trig functions) or for scientific calculations. I would really like to see a higher level calculator set up for business and financial users in an RPN (Reverse Polish Notation) format. As well as being able to do markups and markdowns, I'd like to see the ability to figure loans (mortagages, car payments, etc.). I would also like to have the ability to set the number of decimal places that it displays for the solution (something way more generous than the common 6 or 8 places to the right of the decimal point--preferably user-defined but at least 16 places to the right of the decimal point. There are some business applications that are quite exacting and I would like it if I did not have to carry a specialized calculator with me; I'd prefer to have that capability on my iPhone.