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What: This is one of the well - known vanishing puzzles created by the famous puzzle maker Sam Loyd. Sam Loyd is among the most renowned and historically significant puzzle makers, having published hundreds of thousands of puzzles. The "Disappearing Bicyclist" puzzle is one of my favorites. It uses a simple rotation to conceal the puzzle's secrets while clearly showing how it works.

How To: Operating this puzzle is relatively straightforward. First, count the bicyclists on the screen. Then, click anywhere on the screen and count the bicyclists again. You'll notice that the number goes from 13 to 12, thus presenting the conundrum: where did the extra bicyclist come from (or where did it go)?

Explain it: In this case, although it's difficult to spot (especially in the analog version), each of the boys is divided into small parts. They all seem a bit smaller, and when you do a full count, one of them appears to have vanished. A good approach is to also look at and count the flags.