Get Cold Coming Brain Teaser

What is the fifth daughter's name? ANSWER: Mary.

Well, then riddle me this. Einstein's Riddle is a complicated test of logic that has alternately stumped and pumped intellectuals and would-be enigmatologists for at least a century. Supposedly only 2% of the population are able to solve it.

Ancient and medieval literature is full of riddles. They were used both to bring suspense to the text and to pass on cultural tradition. One example would be the double meanings hidden in the written words that composed the foundation of the knowledge of medieval scholars.

Mathematician Richard Smullyan, nicknamed the undisputed master of logical puzzles by former PhD student Bruce Horowitz, really outdid himself with this brainteaser. As a matter of fact, Smullyan's colleague, an MIT logic professor named George Boolos, called it the Hardest Logic Puzzle Ever and we can see why.

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A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it? Answer: The river was frozen.

1. The World's Hardest Sudoku. Sudoku is easily the most played and most analyzed puzzle in the world, so coming up with the hardest one is no mean feat. In 2012, Finnish mathematician Arto Inkala claimed to have created the "World's Hardest Sudoku".

But, in fact, neither of these obvious choices are actually the first known riddle. The first recorded riddle was from Rhind Mathematical Papyrus and can be dated back to 1650 BC.

One of the earliest known brain teaser enthusiasts was the Greek mathematician Archimedes. He devised mathematical problems for his contemporaries to solve.