Questions tagged [matches]

A puzzle from 2-dimensional or 3-dimensional geometry centered around matchsticks.

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6
votes
3answers
1k views

How many matches can you fit? [closed]

I have a board with some matches on it, in the shape of a number. By adding one match, you make a larger number appear than before. By adding a second match, you make it smaller. By adding a third ...
4
votes
3answers
203 views

Two Fuses Burn for 45 Minutes [duplicate]

You have two pieces of delay fuse. One burns for 1 hour and the other burns for 30 minutes. Without a watch, clock, or timepiece at all... can you beyond any shadow of a doubt tell me when 45 minutes ...
7
votes
7answers
6k views

Make 4 congruent equilateral triangles with 6 matches in 2 dimensions [closed]

How would you make exactly four congruent equilateral triangles with just six matches of equal length in two dimensions? No other triangles may be created when you are done. Matches may not be bent, ...
7
votes
2answers
680 views

A matchstick game

On the table there is a $9\times9$ grid made of matchsticks, so that each of the $81$ little squares is bordered by exactly four matchsticks. Alice and Bob play the following game. Alice and Bob move ...
3
votes
1answer
838 views

Arrange matchsticks so that

Your challenge is to arrange matchsticks to make a pattern. Matchsticks are all the same length and cannot be broken. These are geometric arrangements: Make 4 triangles using 6 sticks. Make 3 X's ...
7
votes
4answers
3k views

Ummm what day was it, a matchstick puzzle

XXIII ------- = II VII All you need to do is move one matchstick from the roman numerals to make the equation true.
9
votes
1answer
516 views

Expected number of squares in a 20x10 grid with 1% chance of removing each edge

Suppose I make a 20x10 grid out of match sticks, using 21 columns of 10 match sticks and 11 rows of 20 match sticks: ...
14
votes
3answers
1k views

Touching Matchsticks

You are asked to place matchsticks on a flat surface such that each matchstick end meets three others, and no matches cross. It is easy to achieve this for patterns that extend indefintely: The ...
15
votes
1answer
1k views

Touching matchsticks with compass and straightedge

The question Touching Matchsticks asked for the smallest matchstick graph where every node is connected to four distinct edges. The Harborth Graph is the smallest such, with 104 edges connecting 52 ...
7
votes
1answer
649 views

Smallest number of matchsticks for a 3D structure with 6 matchsticks at each vertex

Make an as small as possible three dimensional structure of matchsticks, all of which have equal length, such that the end of each matchstick meets exactly five other ends. A matchstick is not allowed ...
3
votes
2answers
280 views

Find seven points so any three contain two of distance one

Choose 7 distinct points in the Euclidean plane so that among any 3 of those points, there are (at least) 2 that are a distance of exactly 1 apart.
7
votes
1answer
414 views

Ten matches on a table

Ten matches lay on a table and look like this: "XI+I=X". They create a correct equality. What is this equality? (Write it in arabic numeral system in your answer).