What's the source of "2.303" in Van't Hoff equation? I've seen a "2.303" term multiplied to $R$ in Van't Hoff equation several times.

Here is one example:

http://en.wikipedia.org/wiki/Van_%27t_Hoff_equation#Error_propagation


  $$\Delta H^\circ=2.303R\frac{\log K_1-\log K_2}{\frac1{T_2}-\frac1{T_1}}$$


What is this number and where does it come from?
It is the multiplier used when converting the equation to use a base 10 log instead of a natural log.

It comes out to be the natural log of 10.