Updated for iPhone 6 and IOS 9.
Operation keys light up to indicate the pending operation.
includes the "-" key to easily input a negative number.
Volume of key presses can be controlled from the phone.
You have a choice of 6 background colors.
Just press the "help" button when you need help.
Will not show scientific notation.
Precision of decimals is accurate to 12 places.
Display will show 38 digits.
Requires Airprint enabled printer or equivalent to print