Scientific calculator

Every function is hand-listed in a parser you can read: no eval, no hidden calls. Arithmetic is IEEE 754 double precision, so sin(30) in degrees reads 1.9999999999999998 rather than a cosmetically rounded 2. Factorial takes whole numbers up to 170, nPr and nCr take n up to one billion with a one million loop-term ceiling, and expressions are capped at 500 characters. What it does not do: symbolic algebra, fractions, matrices, or equation solving. History and the M register live in the page and clear when you reload.