Very difficult logic puzzles

I came across very difficult analytical puzzles over at folj.com.

Short questions, but very difficult to solve.

The first question in the "very difficult logic puzzle" category is:

You are the ruler of a medieval empire and you are about to have celebration tomorrow. The celebration is the most important party you have ever hosted. You’ve got 1000 bottles of wine you were planning to open for the celebration, but you find out that one of them is poisoned.

The poison exhibits no symptoms until death. Death occurs within ten to twenty hours after consuming even the minutest amount of poison.

You have thousands of prisoners at your disposal and just under 24 hours to determine which single bottle is poisoned.

What is the smallest number of prisoners you must have to drink from the bottles to find the poisoned bottle?

What do you think is the answer? 999? 500? Wrong! The answer is a surprisingly small number.

The questions, hints and answers are nicely laid out.

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