From: fizzbintuesday@that-google-mail-domain.com   
      
   This is curious.   
      
   set x=09   
   set /a y=x   
      
   results in the answer zero, but it should give the invalid number error.   
      
   set /a y=%x%   
   does give the expected error.   
      
   BTW I like to use   
   set /a y=(1%x%-100) ...*/-+...   
   as a compact way to remove the zero.   
      
   --   
    Defund the Thought Police   
      
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    * Origin: you cannot sedate... all the things you hate (1:229/2)