John is the owner of a small consulting business.
Last night, some important documents were stolen from John's office.
They were locked up in a safe, and the only way to open the safe was with an 8-digit access code.
Whoever got into the safe must have had that code.
So now he is trying to figure out who could have gotten it.
Only two people in the company were authorized to have the code.
To improve security, John changed the code every month.
He had the code of course, and so did his assistant, Sylvia.
As far as he knew, nobody else had it or had ever asked to use it to get something from the safe.
There was no reason for Sylvia to take the documents, so he couldn't imagine that it was her.
That wouldn't make sense, and she was completely trustworthy.
Besides, she was on a business trip and wouldn't be back for several more days.
So somebody else must have had the code and stolen the documents.
If so, who was it and how did they get the code?
One possibility is that the code was written down somewhere, maybe in a notebook.
Sylvia was famous for writing things down.
She had a notoriously bad memory, so she kept a lot of notes.
Maybe she wasn't careful and someone looked through her notes and discovered the code.
But Sylvia wasn't that careless or irresponsible.
She would never have written the code down on a piece of paper.
So that couldn't be the answer.
