Move one matchstick to make a correct equation. Question made by me (Is this too easy?)

Everyone have me; Without first two letters, I am not here; Without last two letters, I am a story; What am I?

On an ordinary chess board (8x8) without any pieces on it as a starting position, two players will alternately place a pawn on any square (unoccupied) so that the first player that form a square (upright or tilted) with his 4 pieces on the board wins the game. This question mainly search for t...

Once upon a time, long long ago, in the days when good stories were far more beautiful and far harder to come by, a king was asked by his spoilt but beloved princess daughter to give her a fairy tale. In answer to her request, he bestowed upon her a mysterious golden toy. Below you will find a pe...

The following list of words divides evenly into two groups of words which I describe as Triply English and Triply American. American Assault Citation Common Count Diamond Fleet Flying Lord More Rock Sand Sir Slew War West Can you tell me which words belong i...

Amber, leather, fruit, or pine. Whiskey, crackers, never wine. White and red across a sea. Or clad twice in sable, burgundy. Hidden, swung, hooked, flown. Suited, bottled, jumping, thrown. You'll never get me if you're slow. Who I am? Well, "You don't know..."

What thing I'm talking about? Hint-1 Hint-2 Hint-3 Hint-4

Is it possible to decrypt/encrypt something using a Hill Cipher whose key matrix has a size of $100\times100$?

For the purpose of an arithmetical puzzle I am devising, I require a nine-letter legitimate (i.e. acceptable to Scrabble players) English word such that at least one combination of as many as possible of the 511 permutations (without repetitions) of one or more of its letters is itself a legitima...

There’s a pawn starting in the center of this game board. At each move, it can advance randomly towards any of the adjacent squares sharing a common side with equal chance. What’s the probability of landing on the crossed spot on the ninth move?

Here's another around-the-bend. I felt like putting a hidden word in, but I couldn't think of anything good... there's still a word, though. Just unscramble the highlighted letters. Rules Each word goes from left to right on its numbered line, and then continues from right to left on the next ...

I have created a standard sudoku solver using my own algorithm. It relies on a continuous scanning with occasional tuple/pair searching. I am looking forward to test if this works properly. I have hand tested it one some Evil puzzles. Is there any source where I can get extremely hard standard s...