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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How many students turned up for renting the rooms?

Sara has a house which she wants to convert to a hostel and rent it out to students of a nearby women’s college. The house is a two story building and each floor has eight rooms. When one looks from the outside, three rooms are found facing North,…
HOLYBIBLETHE
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Decimal Multiplication Without Multiplication

My friend has recently been challenging me to solve some maths problems, the latest challange is to find a method of finding the answer of $2.5 \cdot 2.5$ without ever using multiplication. Now with whole numbers this is easy, you would just use…
Bornui sndrs
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Maths problem: Cedric's age

We are in the year $2016$, and Cedric's age is a factor of $2016$. If Cedric adds up all the multiples of his age that are less than $365$, he arrives at the year he was born. In which year was he born? I have tried this question numerous…
Tom Finet
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How to arrange 1 to 15 such that the sum of any adjacent 3 numbers will be a perfect cube?

The numbers 1 to 15 should be arranged in a way that any 3 adjacent numbers' sum will be a perfect cube.
Satyam
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Measurement Question Related to a Race Car

I recently got this peculiar interview question, and I wanted some help figuring out how to reach an appropriate solution. Imagine that we have a race car that is driving on a $50$-mile-long race track, and this race car has five minutes to drive…
Ron
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If $2^{2013}-2^{2012}-2^{2011}+2^{2010} = k \cdot 2^{2010}$, find $k$

Hey this is just a question i was having fun with but couldnt solve for some reason. Would love if you can help me solve it thankyou!: If $2^{2013}-2^{2012}-2^{2011}+2^{2010} = k\times2^{2010}$. find k
ewrwr
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Alternative Arithmetics

In Anderson et. al 2010, "Cognitive and metacognitive activity in mathematical problem solving: prefrontal and parietal patterns", the experimenters taught people how to solve a novel system of arithmetic problems, which they termed 'pyramid…
Nathan
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Make all the sixes. Fun

Given the following it is possible to complete each case so that they are all true? (i.e. so that the equation .... = 6 is true) You can add any mathematical operations and parentheses but you cannot add any numbers. i.e. $\sqrt{4}$ is fine but…
Fogmeister
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showing a convex function s subharmonic

Given a $C^2$ convex function $f$ and $u$ a harmonic function in an open subset of $\mathbb{R^2}$, how can I show that $f(u)$ is sub-harmonic?
Herband
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Is 42 in the French Premier League the maximal number of points possible to be relegated?

This is Saturday night mathematics, yet, it is not an absurd exercise The French premier league has 20 teams. After 38 matches (all teams meeting each other twice), the last 3 by point total are relegated to the next division. Points are acquired…
user145413
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Find all reals x, y such that 1<=x<=a , 1<=y <=b and (x^(1/3) + y^(1/3))^3 is integer.

The question was asked in a Twitter interview. For given integers $a$ and $b$, find all reals $x$, $y$ such that $1\leq x\leq a$ , $1\leq y\leq b$ and $(x^{1/3} + y^{1/3})^3$ is an integer.
xperien
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Code Jam 2014 Cookie Clicker Alpha Proof

I was looking at the solution for the Code Jam 2014 qualification question but the proof of correctness seems to be incomplete and I was wondering if anyone could help me with it. The full question can be found here but to summarize: You are given…
Synderesis
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Most Number Of Lowest Numbers

I'm looking for a formula for the following problem. Hopefully I can explain this clearly and it all makes sense. No, it's not my homework, it's part of a competition I'm involved with managing and we're trying to figure out the fairest way to go…
WiLDRAGoN
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Fibonacci spiral in octopus tentacles.

How you happened to notice the presence of the Fibonacci spiral in nature it is really evident. For example, unlike octopuses, squid and cuttlefishes, the nautilus kept its stunning shell, which is well known for its elaborate internal Fibonacci…
Mark
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Is there a formula that will take me from a "given number of digits" to "largest possible integer"?

Apologies for what may be a simple question, but I don't have a background in mathematics beyond high school. I'm trying to work out a formula, that when given a number, say 2, to treat this as "number of digits" and calculate the largest possible…
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