Anne-Marie,

The numbers 0.5 and 0.50 are the same, and both are equivalent to 40 mg Cortef.  Perhaps you are thinking of 0.05?  That would be equivalent to 4mg Cortef.

If it helps to think of it in fraction form, 0.5 is written as 5/10 while 0.50 is written as 50/100.  Either way you write it, it’s a half of a mg.  On the other hand, 0.05 is written as 5/100, or 5% of a mg. 

Fun with math on a Tuesday night...

LauraK