Square root symbol √

Windows

Hold Alt and type 251 on the numeric keypad, then let go of Alt.

In Microsoft Word you can also type 221A and then press Alt+X.

Mac

Press Option+V on a US keyboard layout.

Or press Control+Command+Space, search for “square root” and double-click √.

iPhone

Tap Copy above, then touch and hold where you want √ and tap Paste.

To type it from the keyboard, open Settings › General › Keyboard › Text Replacement, tap +, paste √ as the Phrase and add a Shortcut.

Android

Tap Copy above, then touch and hold where you want √ and tap Paste.

To type it from the keyboard in Gboard, open Gboard settings › Dictionary › Personal dictionary, tap +, paste √ and add a shortcut.

Linux

Press Ctrl+Shift+U, type 221a, then press Space or Enter. This works in most GTK and IBus apps.

Word and Google Docs

Word: type 221A, then press Alt+X.

Google Docs: open Insert › Special characters and search for “square root”.