Help With This Germany 1923 100 Millionen Mark

You will not find it in the Pick catalog. It is hyperinflation notgeld issued by a German business in the city of Stollberg.

That number is not a Pick number, it's a Keller number. Albert Pick had nothing to do with writing the Notgeld catalogues, which are a massive thirty-odd volume set of books originally compiled by Arnold Keller.

And the Keller numbering system isn't quite the same as the Pick numbering, either. Each city is allocated a number; Stollberg is city number 4892. Each series issued within that city is allocated a letter; this note is from the eighth series of notes from that city, in chronological order. Subseries are allocated additional letters or numbers. But the actual note within that series - in this case, 100 million marks - is not allocated a separate number. Thus, the full catalogue attribution ought to read "Keller 4892 h 100 millionen mark".

No, that's just laziness on the part of that website's owner. "Pick number" (with a capital P) should only refer to world notes listed in Pick, never to notes that are not listed in the Pick catalogue; otherwise, people will be scouring the Pick catalogues looking for notes that simply aren't listed there. Just as world coins are listed in Krause, but you would not describe notgeld coins not listed in Krause by "Krause number".