SpeedCrunch is a simple but powerful calculator.
Among its features are:
- high precision, up to 50 decimal digits
- to be enjoyed using keyboard
- result shown in scrollable window
- history of last expressions (use up and down arrow)
- built-in functions: abs, sqrt, pi, log, exp, ln, sin, cos, tan, sinh,
  cosh, tanh, asin, acos, atan, arsinh, arcosh, artanh
- postfix operator ! lets you compute factorials
- support for variables, e.g try x=pi/3 and then sin(x)
- special variable ans holds the last calculation result
- percent operator, try e.g. 45%*75 or price/80%
- angle mode: Alt+D for degrees, Alt+R for radians
- automatic parentheses closing, e.g. cos(pi/4 becomes cos(pi/4)

Homepage:
https://www.speedcrunch.org/
