Time.timeScale and Time.fixedDeltaTime

I'm making a quick menu for my game, when it pops up the game time slows down to 10% normal speed while you do your quick menu stuff. then time speeds back up to 100% when you let off the button. but the scripting reference says i also need to drop down the fixedDeltaTime. but I'm not sure how to do it.

this is what i have currently, it works well enough that i don't notice any messed up physics, but i have no idea what its doing.

 function actionMenu()
 {
     if (Input.GetButtonDown("ActionMenu"))
     {
         Time.timeScale = 0.1;
         Time.fixedDeltaTime *= .1;
     }
     if(Input.GetButtonUp("ActionMenu"))
     {
         Time.timeScale = 1.0;
         Time.fixedDeltaTime /= .1;
     }
 }

in the script reference, the example they give is:

 // Adjust fixed delta time according to timescale
 // The fixed delta time will now be 0.02 frames per real-time second
 Time.fixedDeltaTime = 0.02 * Time.timeScale;
 

i understand the " * Time.timeScale" part but what is the 0.02?