NaN
<math xmlns="http://www.w3.org/1998/Math/MathML"> <apply> <csymbol cd="relation1">eq</csymbol> <apply> <csymbol cd="arith1">divide</csymbol> <cn>0</cn> <cn>0</cn> </apply> <csymbol cd="nums1">NaN</csymbol> </apply> </math>
Author: MathML 2 Recommendation