Challenging Puzzle Similar to the Four 4's

Date: 04/06/2006 at 01:22:24
From: Sam
Subject: Math puzzle

I've been looking all over for the solution to this problem: "Using 
only two 2's and any of the standard mathematical symbols, write an
expression whose value is equal to exactly five."

It must involve a greater knowledge of mathematics than I possess!

Date: 04/06/2006 at 14:46:09
From: Doctor Douglas
Subject: Re: Math puzzle

Hi Sam.

That's a tricky one!  

My solution uses, in addition to the two twos, a decimal point,
a minus sign, and a square root.  Hopefully that gives you enough
of a hint to have the pleasure of figuring it out on your own.

- Doctor Douglas, The Math Forum
  http://mathforum.org/dr.math/