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How do I type the square root symbol (√) in Windows?

2
  • As a side note- that symbol, and the Alt-code to enter it have nothing to do with ASCII. ASCII only defines 128 symbols. – Michael Kohne May 2 '14 at 15:14
  • Well, really only 95 "printing" glyphs, counting the space. ASCII codes 32 through 126, inclusive. 0 through 31 are control codes, and 127 is DEL. – Jamie Hanrahan Mar 29 '17 at 21:34
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In short it's ALT + 251 (note, no preceding zero)

Unicode it is U-221A

http://www.fileformat.info/info/unicode/char/221a/index.htm

If that doesn't work then:

Press and hold down the Alt key.
Press the + (plus) key on the numeric keypad.
Type the hexidecimal unicode value (221A).
Release the Alt key.
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  • 2
    I am getting û for Alt 251 – ajy Oct 12 '11 at 2:04
  • alt-251 is font dependent, so use the unicode sequence alt+221a as above - this will only work in unicode aware apps. Note you can use charmap in most versions of Windows to work out either the alt sequence or alt-unicode sequence. – Paul Oct 12 '11 at 2:31
  • doesn't work. I am using an apple keyboard on a windows machine. Could that be a problem? – ajy Oct 12 '11 at 4:08
  • I am afraid it doesn't work for me – Jess Stone Jul 14 '14 at 15:24
  • 1
    I am getting ¹ for Alt+251 – sergiol May 19 '15 at 7:33
2

Open regedit.exe

Navigate to HKEY_CURRENT_USER\Control Panel\Input Method and add a string or REG_SZ value EnableHexNumpad. Set the value to 1. Log out and log in.

Now you can use ALT <numpad +> 221A

As for why your ALT codes don't work:

Manufacturers of PCs have character sets in their hardware/firmware. These are called OEM code pages by Windows. Windows also has a standard Latin character set for english speaking regions called Windows-1252, which it uses for most non-unicode programs. When you type ALT 251 ¹ you use the OEM set which can vary between each PC (Mine is code page 850). When you type ALT 0251 û, it uses the Windows-1252 character set.

Some others were saying that ALT 8730 or ALT 08730 <substitute (SUB) character> works but from my experience, any value above ALT 255 or ALT 0255 just gets converted back to a value between ALT 0 and ALT 255.

1

I used charmap and seeked to the position where the character U+221A is, clicked the buttons Select and Copy, then I pasted it where I wanted to use it.

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Alt 251 didn't work for me, nor did alt +... but alt 8730 did (0x221A in decimal), i.e. hold alt, type 8730 on the numeric pad, release alt.

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    →, doesn't work. – redbeam_ May 12 '15 at 18:45
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The actual (alt+X) codes didn't work, so I went into Symbols (using MS Word), used the Unicode (211A) to find squareRoot, and then added a shortcut to the symbol for easy access. I used (CTRL+{).

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