Unless you have been liv­ing in a cave, you have read by now mul­ti­ple arti­cles about the brain train­ing and brain exer­cise craze: sudoku, Nin­ten­do BrainAge, mul­ti­ple online games, soft­ware like Mind­Fit and Posit Science… If you are look­ing for some fun men­tal stim­u­la­tion now, here you have our selec­tion of Brain Teasers. Now, how…