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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Interesting problem from brother's test prep

SEND + MORE = MONEY Each letter represents a single digit number. No two letters represent the same number. (Ex: if M=1 the no other letter in the problem can equal 1) So far we've figured out that M=1, O=zero, and S is either 8 or 9 This is a very…
John smith
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Sharing items to a particular number of people

If I have a game where everyone contributes money, but only $n$ ($11$ in this case) people can win. How do I share the winnings such that the prize amounts do not diverge significantly as the amount contributed increases? If I have winnings a, b , c…
Inemesit Affia
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Maximum number of chess moves

Chess has a limited number of maximum moves because of the 50-move rule (50 moves without any captures or pawn moves results in a draw). There are 30 capture-able pieces, and I've figured out that the number of pawn moves can be maximized in this…
user80458
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Mathematics in Football- Foul play and goal-scoring opportunity

I am reading an article talking about the mathematics in football (link: https://plus.maths.org/content/ball ). In the second part, it asks if a player should risk being sent off in order to gain the opportunity of having a goal, providing that a…
Nighty
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Theoretical insect population growth limit

Fire Ant mounds are rising in my yard: if a mound can have only one queen, and she lays $50$ viable eggs per day, and if $2\%$ of the population dies per day, what is the limit of population growth? Obviously, when the death rate equals $50$ per…
BigTex
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Anyone know of a good composite number counter?

I am looking for a chart that would show how many composite numbers there are under "n" broken out by how many factors they have. Has anyone seen a chart like this? Example information I am looking for: composite numbers under 20 total: 11 with 2…
Joe
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There's addition, multiplication and exponentiation. Is there another "level" after exponentiation?

I guess they all can be broken back down into addition but I just have always had this burning question if there was some other mystery operator after exponentiation.
Chris W
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How do you solve for x in this equation? $4^x=2^x+6$

$4^x=2^x+6$ Given that $x$ is in the form "log base $a$ of $b$" and both $a$ and $b$ are prime numbers, what is the ordered pair $(a,b)$: I have no idea how to solve this, I've been staring at it for hours now and no matter what I do I cannot seem…
bbuddy27
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Finding argmin$_{n \in \mathbb{N}} |2^{n/12} - 5|$ non-computationally

The problem is to find the integer $n$ such that $|2^{n/12} - 5|$ attains its minimum. Since it is clear that $24 \leq n \leq 35$, by computation one easily gets $n = 28$. However, how to find this $n$ without any calculator?
Yes
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proving onto function of composite functions.

Let $X, Y, Z$ be arbitrary sets. Suppose $\alpha$ is a function from $X$ to $Y$ and $\beta$ is a function from $Y$ to $Z$ such that $\beta\circ\alpha$ is an onto function. How do I prove that $\beta$ is an onto function? I always get confused when…
Techwatch
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Multiply large numbers

Consider the product $723145878987 \times599987871$. If I want to know that what would be sum of unit and tens digit of the result then Is there a trick that I could find it as fastly as possible?
Edison
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An recreational question on analysis

Alice and Bob ran a marathon ($26.2$ miles) with Alice running at a uniform $8$ minutes per mile pace and Bob running erratically, but taking exactly $8$ minutes and $1$ second to complete each mile interval - that is to say all intervals of the…
FunctionOfX
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How do you solve "sum of ages" puzzles?

Ma and Pa and brother and me. The sum of our ages is eighty-three. Six times Pa’s age is seven times Ma’s age, and Ma’s age is three times my age. What is Pa’s age? What is Ma’s age? What is my brother’s age? What is my age? I try setting up…
Acade
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The fly flying between two trains

I know this question has been posted many times, but I don't understand it. Two trains travel on the same track towards each other, each going at a speed of 40 kph. They start out 180km apart. A fly starts at the front of one train and flies at 100…
Majky28
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What's the difference between nothing, zero, and the empty set?

I'm a novice in math, just learning the basics as of the moment and I'm naturally out of me depths when it comes to the real rigorous and technical stuff. I would like some help understanding some concepts in the subject (vide infra) Nothing (Zero…
Agent Smith
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