Mathematics Stack Exchange
Mathematics Stack Exchange

Questions tagged [recreational-mathematics]

Mathematics done just for fun, often disjoint from typical school mathematics curriculum. Also see the [puzzle] and [contest-math] tags.

Recreational mathematics is a general term for mathematical problems studied for the sake of pure intellectual curiosity, or just for the enjoyment of thinking about mathematics, without necessarily having any practical application or expectation of deep theoretical results.

Recreational mathematics problems are often easy to understand even for people without an extensive mathematical education, even if the theory they lead to may turn out to be surprisingly deep. Thus, recreational mathematics can serve to attract the curiosity of non-mathematicians and to inspire them to develop their mathematical skills further.

Many typical recreational mathematics problems fall into the fields of discrete mathematics (combinatorics, elementary number theory, etc.), probability theory and geometry. Important contributors to recreational mathematics are Sam Loyd and Martin Gardner.

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Discovering how the number Mind Scanner mobile app works.....

Yesterday I downloaded a mobile app.Many of you may have also seen it.The working is as follows- Think of any two digit number from 10-99 Sum up the digits of the number and subtract it from the original number. You get a number.Now compare this…
Soham
  • 9,990
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Is it possible to test $x > c$ and $y > c$ using only one condition?

Is it possible to test $x > c$ and $y > c$ using only one condition? If it's not possible within $(-\infty,+\infty)$, is it possible in $[0,1]$ ? Thanks,
Nison Maël
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Find $n$ if $n!$ ends in exactly $100$ zeroes and $n$ is divisible by $8$.

This question was in school maths challenge. I dont know how to approach this one.. any help would be appreciated.
Abu Bardewa
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Recreational Maths IMO

I saw this problem on a maths challenge book. Given any set $A=\{a_1 ,a_2, a_3, a_4\}$ of four distinct positive integers, we denote the sum $a_1+a_2+a_3+a_4$ by $S\{A\}$. Let $n_A$ denote the number of pairs $(i,j)$ with $1\le i\le j\le4$ for…
Abu Bardewa
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Is there a formula to find every number divisible by $7$ but not $2,3$,or $5$? Not counting numbers but looking for specific solutions.

All numbers divisible by 3 but not 2 can be found using $6*n+3$ All numbers Divisible by 5 but not 3 or 2 can be found using $10*n+5$ Is there a formula for divisible by 7 but not 5,3,or 2?
Joe
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Fun math books for 8 year old with math aptitude

My 8 year old showed interest and aptitude for math well above the level they teach in her school. I would like to find some math books that would spike her interest in math and make it fun for her.
ned
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The Regular Pentagram

Consider a regular pentagon circumscribed in a circle. Connect each vertex of this pentagon to every other not adjacent to it with a straight line segment to obtain a pentagram which contains a smaller pentagon. What is the ratio of the area of…
user259083
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Why is the Connect Four gaming board 7x6 (as opposed to 8x8, i.e. 2n by 2n)?

The Connect Four board is 7x6, as opposed to 8x8, 16x16, or even 4x4. Is there a specific, mathematical reason for this? The reason I'm asking is because I'm developing a program that will be able to generate Connect $N$ boards, for any given…
chrisdotcode
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The jackal, the lion, the parrot and the giraffe - logic puzzle

Here is a puzzle that appeared in a Russian magazine named Kvantik (see Tanya Khovanova's Math Blog). [The trick lies in that we don't know exactly what the hedgehog knows at each stage. The symbology of the animals and their behaviour is great…
Marconius
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Is it possible to create horizontal lines of arbitrary length in match-three games?

Bejeweled. Candy Crush. A match-three game always follows the same basic rules, with each one adding its tweaks to gameplay. A mathematician would describe the state of one such game as a two-dimensional matrix whose elements ("blocks") range in a…
MathET
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Helping 7th grade with math question... I'm stumped.

First salesperson says 7 baubles together with 5 gewgaws is the same value as 6 trinkets Second salesperson says 4 baubles with 9 trinkets has the same value as 5 gewgaws Third salesperson says 6 trinkets with 3 gegwaws has the same values as 4…
brettwgreen
  • 153
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Tower of Hanoi solutions for non-legal initial configuration

I just found an Towers of Hanoi game (see http://en.wikipedia.org/wiki/Tower_of_Hanoi) messed up by a someone to one tower not obeying the rules, eg. large and small disks where interleaved. I just played the game to the rules, and finally came up…
dronus
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Find the number of all 3 digit numbers $n$ such that $S(S(n))=2$

For any natural number $n$ ,let $S(n)$ denote the sum of the digits of $n$.Find the number of all 3 digit numbers $n$ such that $S(S(n))=2$
Snehil Sinha
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Calculating equal playing time in a soccer game with minimum number of changes.

I need to produce a formula that takes the following parameters: T = time of game in minutes p = number of players on field at one time s = number of substitute players Each of these is variable on a game-to-game basis but once the game has begun…
Matt Oakley
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Brainteaser Switches

You have four switches that could be on or off that are configured in a 2x2 grid. You are given an initial configuration that is random and you are blindfolded. (a) Can you possibly find the configuration where they are all on? (trivial, consider…
Jasper
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