Iphone & Droid Calculator application

Hey guys, I have been asking people about what they would think about a calculator application that would allow you to use your iphone to calculate NPV, IRR values to even monthly car payments and so on.

For those of you who have worked at investment banks as interns, you probably remember the analyst or the associate using their HP 12C calculators or the Ti's while in a meeting just to adjust a few numbers or to just verify that the numbers in the presentations are correct. What if you didn't need a calculator and can just use a calculator on your iphone, that would allow you to easily enter a few values and calculate banking related figures in seconds.

I know many applications exist, but they are either expensive or just not as user-friendly as I want them to be. And since I will be starting my job in July at an Investment bank, I have a few months to start an app and I figured, why not create an application that's either cheap or free, that would make life easier for bankers everywhere. The advantage of this application would be that you can customize your own calculator, depending on whichever functions you use the most. It is going to be very user-friendly and will have a large display screen, so that you can view previous calculations you have made, just like on a calculator.

Let me know what you guys think. Secondly, if there are other functions that you think that the calculator should perform, please let me know. Thank you and I appreciate all the feedback.