Windows: press `Alt + 0176` on the numeric keypad
Mac: press `Option + Shift + 8`
iPhone/iPad: press and hold `0`, then select `°`
Android: press and hold `0`, then select `°`
Copy and paste this symbol: `°`
In Microsoft Word: type `00B0`, then press `Alt + X`
In HTML: use `°`
In LaTeX: use `^circ`