FORTRAN tip calculator
To build, use gfortran:
$ gfortran -o tipcalc tipcalc.f
To run, type:
$ ./tipcalc
You will get a prompt labeled "Enter subtotal:" followed by a newline. Enter your subtotal, and press return. The program will then ask you for a percentage. Enter the percent of the bill you want to tip. The program will return the tip amount, and the total, and then terminate.