How to Solve Picture Logic Puzzles: Fill-by-Number Grids
Read row and column clues as blocks, use overlap and exact fit, and reveal the hidden picture. A worked five by five puzzle and a practice grid.
Riddle10 blog
The Riddle10 blog
The Riddle10 blog explains riddles and puzzles one step at a time. Read why the answer to a well-known riddle works, try sets of original riddles with answers, or learn a method for logic grids, number sequences, cube nets and other classic types. Each guide uses a worked example, and the history section looks at where puzzles come from and what makes them hard.
Why Some Peg Solitaire Puzzles Are Unsolvable
A colouring trick shows why some peg solitaire puzzles can never end with one peg, and what research found about symmetric and unique-solution boards.
Dissection Puzzles: Cutting a Triangle Into a Square
Any polygon can be cut into any other of equal area, but how few pieces? Why four convex pieces is the record for turning a triangle into a square.
Tangram Puzzle Solutions: A Step-by-Step Method
Place the large triangles first, read the corners and flip the parallelogram. Seven pieces, their size rules and nine verified tangram solutions.
Types of Logic Puzzles: Nine Kinds and How to Start Each
Grid, truth-teller, weighing, sliding tile, peg, knight's tour, packing, maze and sequence puzzles: what each logic puzzle type is and how to begin.
Logic Grid Puzzles: How to Solve Them With X and Tick
Mark X for no and tick for yes, use the only-one-left rule and chain clues across the grid. A full worked logic grid puzzle and a practice puzzle.
How to Solve Brain Teasers: 8 Tools and When to Use Them
Eight solving tools matched to the four types of brain teaser, with five worked examples and the mistakes that trip people up.
How to Solve the Knight's Tour Puzzle, Step by Step
Visit every square once with a knight: the move, open and closed tours, the colour rule, a smart rule of thumb, and fully worked 5x5, 6x6 and 8x8 tours.
Chess Board Puzzles: How Many Queens Fit, With and Without Pawns
From eight queens to a quarter of the board: what peer-reviewed papers say about queens, pawns, dragon kings and the distance between squares.
How to Solve a Sliding Tile Puzzle, Step by Step
Top row first, then the left column, then repeat. A clear method for the 8-puzzle, the 15-puzzle and larger trays, with the trick for the last two tiles.
Truth-Teller and Liar Riddles: How to Solve Them
Assume, test, and look for the clue that rules out the mirror answer. A clear method for truth-teller and liar logic puzzles with worked examples.
How to Solve Coin Weighing Puzzles, Step by Step
Split the coins into three groups, not two. A clear method for balance scale puzzles, from 9 coins in 2 weighings to the classic 12-coin puzzle.
Crack the Lock Riddle: Which 3-Digit Code Opens It? Answer: 738
The code is 738. Learn how the gold dots and rings rule digits in and out, and the order that makes code lock riddles quick to solve.
The Three Fruits Logic Riddle: Which Fruit Does Huda Have?
Huda has the fig. See how two short clues settle all three fruits, and how to solve small matching riddles with a grid.
Roll the Cube Riddle: Which Symbol Is on Top at the End?
The triangle ends on top. Follow the cube roll by roll along the path, plus a shortcut for rolling cube riddles that saves most of the work.
Fold the Net Riddle: Which Cube Folds From This Net? Answer: B
Cube B is the answer. Learn how to fold a cube net in your head, which faces end up opposite each other, and why cubes A, C and D cannot be made.
Three Level Scales Riddle: How Many Circles Balance the Last?
The answer is 5 circles. See how three level scales show that a square weighs 2 circles and a triangle 3, and why 2, 3 and 6 are wrong.
Packing Puzzles: The 70 Square and the Thirty Colour Cubes
Why 24 squares cannot tile a 70 square, how a shorter proof is being built from the edges, and how 30 painted cubes copy each other.
What Is a Puzzle? A Definition From Mathematics and Puzzle Design
A puzzle has a fixed start, fixed rules and a clear goal. What research says makes a puzzle good, what makes it hard, and when it has no solution.
I Grow in the Field Riddle: The Answer Is Wheat
The answer is wheat. Drop the W for heat, drop the H for eat. See why wheat fits all three clues and which guesses fall short.