It’s a simple log function. Log(Radius(m)) = -3 would be 1 cm. 1*10^-3 m = 0.1 cm. At Log(Radius(m)) = -2 where most of the density ends, the radius would be 1 cm.
Their statement is pretty self-explanatory. If you don’t get it then you need to go back and take some remedial science and math courses. Your constant confusion with log functions suggests you probably should do so anyway. Please, drop this nonsense, it’s making free republic look ridiculous. There are plenty of forums on the internet for pseudoscientific discussions. I’m begging you, this is embarrassing.
Should be .1 cm, not 1 cm.