[TheAceOfHearts]

This past week I was reading Neverwhere, by Neil Gaiman which has the same interaction:

> "Now me," said Mr. Vandemar. "What number am I thinking of?"

> "I beg your pardon?"

> "What number am I thinking of?" repeated Mr. Vandemar. "It's between one and a lot," he added, helpfully.

> "Seven," said the marquis. Mr. Vandemar nodded, impressed.

When I encountered the question the first number that popped into my head was also seven. This was immediately followed by the thought that if I were the one picking a number I should explicitly avoid seven. Does this question and answer pair give anyone else a strong feeling of déjà vu? I think this interaction is a meme [0].

It's also interesting that most people will limit their choice to a (whole number | positive integer). The best choice is probably an irrational number like the square root of two (√2) or pi (π). Although those are still relatively predictable since most people would probably make their selection from the small set of well-known irrational numbers, so you should go one step further and add to or multiply the value.

[0] https://en.wikipedia.org/wiki/Meme

[gizmo686]

Your best choice is probably to stick with rationals, and just list off an arbitrary number of digits to the right of the decimal.