<math> <apply> <eq/> <apply><divergence/><ci type="vectorfield">a</ci></apply> <apply> <limit/> <bvar> <ci> V </ci> </bvar> <condition> <apply> <tendsto/> <ci> V </ci> <cn> 0 </cn> </apply> </condition> <apply> <divide/> <apply><int encoding="text" definitionURL="SurfaceIntegrals.htm"/> <bvar> <ci> S</ci> </bvar> <ci> a </ci> </apply> <ci> V </ci> </apply> </apply> </apply> </math>