How to turn iPhone into engineering calculator

Hewlett-Packard Company has announced three-phone applications for iPhone, with which you can turn it into one of three classical engineering calculators. Of course, this applies only to the external design of the screen, but applications are changing not only its appearance but also have all the original functionality of the device.

Since the iPhone has a processor much more powerful than those used in calculators, it believes it is much faster. In addition, applications using the sensor information: calculator can change orientation from horizontal to vertical, and rotating displays «back panel» written on it with the most common formulas.
Version imitating calculator HP 12c and HP 15s is available for download at iTunes App Store (the value of their $ 15 and $ 30), a version of HP 12 c Platinum will be available in August for $ 20.