Windows
Hold Alt and type 24 on the numeric keypad.
Arrows
Copy the character, or use the shortcut that matches your keyboard and app.
Hold Alt and type 24 on the numeric keypad.
Character Viewer → arrow
Type 2191 then Alt + X
Insert → Special characters → arrow
Click the keycap, then paste with Ctrl+V or Cmd+V.
Num Lock on, hold Alt, type 24, release Alt.
Use the Unicode, HTML, CSS, or JS value below in documents and stylesheets.
U+2191↑↑\2191\u{2191}Alt + 24