DozenCalc

A dozenal (duodecimal, or base-twelve) calculator with both
simple and scientific modes. Simple mode (automatically
chosen when in portrait orientation) contains the four
functions, square roots, exponents, and parentheses for
grouping, and operates to four digits of fractional
accuracy. Scientific mode (automatically chosen when in
landscape orientation) has all of the same features, plus
trigonometric functions and their inverses, logarithms,
reciprocals, buttons for pi and the base of the natural
logarithm, and variable precision allowing the user to
select the number of fractional digits desired.