Ugh, the level to which this has been mis-quoted shows a lack of understanding by the TPM authors bordering on idiocy.
The previously made sheet of graphene was cited to be 76 centimeters square. but the original article
http://www.rsc.org/chemistryworld/News/2010/June/20061001.asp notes that the sheet was 76 Centimeters
on the diagonal which would be 54 centimeters on a side if it was a perfect square:
2916 square centimeters.
So if we were to use their own retarded logic system, the claim of attempting a sheet that was one kilometer square, that would actually mean one kilometer on the diagonal. so a centimeter wide and just under a kilometer long would suffice to satisfy the claim.