Brain games: puzzles, riddles, and logical games.
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Numbers in a square Patterns and correspondences  Weight: 1 Liked the puzzle: 80% 24.12.2011
Place numbers 1,2,.., 9 without repetitions into a 3x3 square so that the sums in all rows, columns, and diagonals are all equal.
Comments:  1 check your solution  
Links and chains Logic puzzles  Weight: 1 Liked the puzzle: 100% 02.04.2011
Once upon a time, a Megamind worked as a smith. He was brought 5 chains each consisting of 3 links. What is the minimal number of links that the Megamind should re-lock to make one long chain?
Comments:  1 check your solution  
Vases and beads Patterns and correspondences  Weight: 1 Liked the puzzle: 100% 24.12.2011
A Megamind on his treasure hunt discovered a cave with six ancient vases. Unfortunately, instead of treasures, the vases contained beads. The first vase had 60 beads, the second had 30 beads, the third had 20 beads, and the fourth had 15 beads. How many beads were in the fifth and the sixth vases, given that these number form a certain pattern?
Comments:  2 check your solution  
Two incense sticks Logic puzzles  Weight: 1 Liked the puzzle: 100% 27.12.2009
You have two incense sticks, that burn unevenly, and a lighter. Each will burn for an hour. How can you time 45 minutes using nothing but these tools.
Comments:  4 check your solution  
Two villages Knights, Knaves and Jokers  Weight: 2 Liked the puzzle: 100% 27.12.2009
A Megamind is lost in the mountains. He is standing on a path, shouting for help. Finally, he sees a local approaching. Megamind knows that the locals can be knights that always tell the truth, or knaves that always lie. He also knows that the path leads to the village of knights in one direction and to the village of knaves in the other. The problems is that the knaves are also hateful of Megaminds, and will stone him if gets to their village. How can Megamind ask one question and determine the right way to go?
Comments:  4 check your solution  
Numbers on the fence Patterns and correspondences  Weight: 2 Liked the puzzle: 100% 31.12.2009
A Megamind walked along a fence and discovered strange pairs of numbers. First, he saw "188->4". A bit farther, he discovered"232->0". A few steps after that, "100->2". Then, "163->1". Then he saw a little boy who was just beginning to paint something. When the Megamind called the boy, he ran away. Approaching the site, the Megamind saw an incomplete pair "386->...". He took out his favorite marker and completed the pair. What number did he write?
Comments:  1 check your solution  
Obtain 24 Algebra, arithmetic  Weight: 2 Liked the puzzle: 100% 27.12.2009
Using numbers 1,3,4,6, and basic arithmetic operations (addition, subtraction, multiplication, and division) and parentheses, obtain and expression that evaluates to 24. You may use only these numbers and only these operations. Every number should be used exactly once. Numbers cannot be concatenated, i.e. you cannot use 13 or 146.
Comments:  7 check your solution  
101 coins Weighing puzzles  Weight: 3 Liked the puzzle: 100% 04.01.2010
Among 101 coins, exactly 50 are counterfeit. A counterfeit coins weighs one gram more or gram less than the real coin (counterfeit coins may weigh differently). You have a balance scale that shows the exact weight differential between the two cups. How can you determine whether a given coin from this set is counterfeit using the scale only once?
Comments:  1 check your solution  
The fifth number Algebra, arithmetic  Weight: 3 Liked the puzzle: 100% 09.01.2010
The set of numbers 1,3,8,120 has a remarkable property: the product of any two numbers is a perfect square minus one. Find a fifth number that could be added to the set preserving its property.
Comments:  4 check your solution  
50 coins Logic puzzles  Weight: 3 Liked the puzzle: 100% 27.12.2009
Once upon a time, a tsar was holding a reception and the Megamind was among the guests. The tsar decided to test how smart the Megamind was, took him into a dark room, and gave the following task: On the table in this room, there are 50 coins, exactly 10 of them are tails up. In the darkness, it is impossible to determine the sides of these coins. Touching the coins also does not help. The Megamind has to separate these coins into two groups so that the number of tails in both are equal. Can he do it?
Comments:  4 check your solution  
A Megamind in a boat Geometry puzzles  Weight: 4 Liked the puzzle: 100% 27.12.2009
A Megamind is sitting in a boat at the center of a circular lake of radius R. On the lake shore, an evil Goblin awaits. Luckily for the Megamind, the Goblin can only move along the shore. Unfortunately, the Goblin is 4 times as fast as the Megamind in his boat. The Megamind can save himself if he gets to the shore and evades meeting with the Goblin. Can the Megamind save himself? If yes - how?
Comments:  1 check your solution  
A game with coins Games puzzles  Weight: 4 Liked the puzzle: 100% 12.03.2011
Two Megaminds play a game: they have a regular round table and an unlimited supply of identical round coins. Turn by turn, they place coins on the table until someone can no longer make a move. The coins cannot overlay each other, but they can touch. Who has a winning strategy (and what is it) in this game?
Comments:  6 check your solution  
Tic-tac-toe, the Megamind style Games puzzles  Weight: 4 Liked the puzzle: 100% 26.02.2011
Two Megaminds decided to play tic-tac-toe using new rules. They use a regular 3x3 playing pad, but each player can choose to place either an X or an O into one of the cells. The winner is still the one who arranges three X's or three O's in a line. Is there a winning strategy in this game? Which player has it?
Comments:  1 check your solution  
Four spheres and a cylinder Geometry puzzles  Weight: 5 Liked the puzzle: 100% 26.01.2010
Four spheres and an infinite cylinder are arranged on a plane so that all these solids touch each other and the plane. The cylinder has radius 1cm. Describe the spatial arrangement of these solids and find the radii of all spheres.
Comments:  7 check your solution  
A poisoned chocolate bar Games puzzles  Weight: 5 Liked the puzzle: 100% 26.12.2009
A chocolate bar consists of NxM (at least two) square pieces arranged in a rectangle. The square in the upper left corner is poisoned. Two players break off the squares from the bar and eat them. If a player chooses a certain square, he must also take all of the remaining squares that have row/column numbers not less than the chosen one. A player forced to take the poisoned square loses. Prove that the first player to make a move has a winning strategy.
Comments:  3 check your solution  
Divide a parallelogram Geometry puzzles  Weight: 5 Liked the puzzle: 100% 02.04.2011
How to divide a parallelogram into 9 isosceles triangles?
Comments:  1 check your solution  



 
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