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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Math behind neodymium ball magnet toys?

Is there some theory behind zen magnets/buckyball-style toys? Did somebody study what forms you can make out of N magnets? Will given form be stable and not be teared apart by magnetic force? How to construct a form closest to given free-form…
gordon-quad
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How to find an odd prime factor of $F(2013)$?

Here, $F(0) = 0, F(1) = 1,$ and $F(n) = F(n − 1) + F(n − 2)$ for $n ≥ 2.$ Please give hints, not full answers. Thanks!
uuuuuuuuuu
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The coast of a river

On the coast of a river, there are four docks : A, B, C, D (in that order). It takes a ferry two hours to get from point B to point A, one hour from point B to point D and three hours from point C to point A. In what direction does the river flow -…
McLinux
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Three math riddles

a)"You give me 100 dollars", said the brother to his sister,"so that we can have the same sum of money." How many more dollars did the sister have in comparison to the brother in the beginning? b)Pears are two times more expensive than apples. Which…
McLinux
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Is it possible to solve recursive percent equations?

I'm working on a program that calculates the skill level of a sports teams based on how well its done against other teams. Something along the lines of, your skill is +20% of the average skill of the teams you beat. This quickly becomes a math…
amflare
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Solving the 24 Game for 5, 5, 5 and 1

The 24 Game is an arithmetical card game in which the objective is to find a way to manipulate four integers so that the end result is 24. How do you get $24$ using $5, 5, 5,$ and $1?$ Solution:…
clache547
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Finding the speed

Charles and Smith left a place abc at the same time and stated moving in the same direction.Charles speed was $15$ Kmph and Smith's speed was $12$ kmph.Half an hour later Anthony left the place and and travelled in the same direction.Sometime later…
Tapadia Lion
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Finding the time taken to complete the work

In a call centre, $6$ employees working for ten hours can complete a certain task. They started working at 11 am .They continued till 5 pm. After that, each hour one more employee is added till the work gets completed. At what time will the work…
Tapadiabeetle
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Bribing a friend for money (game)

Here's how the game works: I get a pay bonus. I'm so happy I decide to give away $100$ dollars to one of my $n>1$ friends. My friends try to bribe me to get the money for themselves; I'm a sucker for bribes so I give the money to the highest briber…
MT_
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Create a formula to compare different exchange rates (one with a fee)

While looking at exchange rates for an upcoming vacation, I decided to brush up on some old math but wanted to make sure I was thinking about it correctly. $B_1$ charges a rate for USD to EUR conversion of $0.85$ but charges a shipping fee ($F$). I…
mrturtle
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How do I write n ∈ all of the known number sets

If I want to say that n ∈ all of the known number sets do I have to write n ∈ $\mathbb{N} , \mathbb{Z} , \mathbb{Q} , \mathbb{R} , \mathbb{C}$ or should I just leave it blank?
OpenHax
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Adding the intersections of circles.

Given the grid attached, how can you place the numbers $1-20$ at the intersections so that each circle adds to the same sum. I haven't been able to figure this out.
user342769
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Algebraic manipulation from $a^2+b^2 = abm$ with all variables in Z to a|b?

I know that $a^2+b^2=a\,b\,m$, with $a,b,m$ integers ($a,b$ positive integers) How can I show that a|b from this? I know it's true intuitively. I can recall the definition of divides to be $ak=b$ such that $k$ is in $\mathbb{Z}$.
Adraj
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"Canceling Out The Zeroes" In A Mathematically Sane Way $\frac{0\times x}{0\times 1}$

Introduction Lets look at the product sequence: $$(n-1)(n-2)(n-3)...(n-k)$$ Where $n,k\in \mathbb N$ and $n\le k$ ; the expression will always have value $0$ But what if we remove the $n$th term in the sequence for choosen $n$? How would you then…
Vepir
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balancing stats for equality

Not sure if this is the right forum, please comment on the correct one. OK: I am creating a game where the user inputs stats and attack values, and I want the ai to match its ability (so they are about equal) for example, "Health": 1000, …
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