Calx: Stack calculator

CALX is an RPN calculator — a calculator designed to work with a list of numbers.
This means that instead of just typing an equation into your calculator, you push numbers onto a stack, and then apply operations to the lowermost numbers in the stack.
It's bizarre, but it makes sense once it clicks.
If this all sounds confusing, don't worry! CALX comes with a guided tutorial which will get you up to speed in three minutes.
Features:
• Gestural interaction: Manipulate your data with simple, intuitive gestures.
• Multiple keypads: CALX features an array of basic, scientific, and statistical functions.
• Customization: Select from different fonts and colours to find a combination that works for you.