Often overlooked, the macOS calculator has two power user modes in addition to its default simple Basic mode.
The Basic mode: Perform simple arithmetic operations.
The Scientific mode: Use memory functions and perform advanced calculations involving fractions, powers, roots, exponents, logarithms, trigonometry, and more.
The Programmer mode: Perform binary, octal, decimal, and hexadecimal calculations, including bitwise operations. You can also view the ASCII and Unicode characters represented by the current value.
To switch between modes, simply press Command + 1 for Basic, Command + 2 for Scientific, and Command + 3 for Programmer, or go to the View menu with the Calculator open to select the mode you wish to use.
Another often overlooked feature of the Calculator is the Convert tools menu. Enter the original value, choose Convert in the menu, then choose one of the following categories: Area, Currency, Energy or Work, Length, Power, Pressure, Speed, Temperature, Time, Volume, Weight and Masses.