Brain teaser: Can you crack the code and find the missing number in the triangle? A popular online math puzzle involves finding a missing number in triangles by using a simple addition rule ...

Alongside the mind-boggling brain teaser, he wrote, “Can you still crack the code?” The brain teaser features a lock that can only be opened with a four-digit code.

Imagine a number lock with a three-digit code, and you're given five clues to crack it open. First, one digit is in the correct spot. Second, one digit is right, but it's in the wrong place.

Does that make it easier to crack the code? Because there are only 25 possible keys, Caesar ciphers are very vulnerable to a “brute force” attack, where the decoder simply tries each possible ...

Crack the Code is a codebreaker game for the iPhone and iPod Touch. The computer chooses a sequence of colors and you must try to guess the sequence within a specific number of guesses.