What are the alt codes for root (?), pi (?), and plus minus (±)?

[Unknown]

I looked those up but the alt codes have changed. Also, if you have any additional codes for useful math symbols, do let me know. Thank you.
@ Java: I've already checked that site, the root symbol and the pi symbol are inaccurate
@ Yawn Gnome: Are you able to simply give me the alt codes? I do not wish to recreate them myself

 

[YawnGnome]

What OS. Is still basically UNIX, GNU/Linux is NOT UNIX, or that is the story they are sticking to.
You are always root and you are never /root. (while on-line)

 

[Java]

http://usefulshortcuts.com/alt-codes/maths-alt-codes.php