NumWiz - Free

NB: This is a special implementation of the free version of the app in which in-app billing is disabled. It was developed to accommodate users whose countries are not supported for in-app purchases.

The free version of this app includes a well designed scientific calculator, along with a converter that allows you to convert angle, area, currency, energy, length, power, pressure, speed, temperature, time, volume and weight. Get the full version for a range of additional functions and features.

In addition, the app has awesome features, such as the ability to read answers aloud.