The square root of two is a fascinating number with a long and sordid history. It also forms the basis of most office paper, such as A4, A3, etc. Website: http://www.numberphile.com/ Numberphile on Facebook: http://www.facebook.com/numberphile Numberphile tweets: https://twitter.com/numberphile Videos by Brady Haran This video features Professor Roger Bowley and Dr James Grime. More about our contributors at www.numberphile.com/team