Turn an octal file mode into the symbolic form, the decimal value and a plain reading of who can read, write or execute.
An IPv4 CIDR into its network address, netmask, broadcast, total and usable host counts and the first and last usable host, with the address as a 32-bit integer and back.
Compare two semantic versions the way semver actually orders them, sort a list, and see what a caret or tilde range resolves to.
Make a URL slug from a title: accents stripped, separator and length controlled, collision checked.
Convert any number between bases 2 and 36, with binary, octal, decimal and hex side by side plus a Roman numeral readout.
Prime factorisation by trial division, every division step, the full divisor list, plus GCD and LCM of two numbers.
A real expression parser: tokenise, shunting-yard to postfix, then evaluate.
Build a wedding budget by category, track what is paid, and see what is still owed.
