RPN iCalc is a BIG button Reverse Polish Notation(RPN) calculator. The calculator takes up the entire screen on all devices including the iPad pro. There is no limit to the number of items that can be input into the stack. The last two items in the stack are always visible. So, you can always see the values that apply to the operation.
RPN iCalc allows you to set the accuracy from a four to sixteen digits past the decimal place.
There is also an option in that settings file that enables are disables the speak results feature.