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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bucket numbers by range

I have a list of numbers: 0,1,2, 200,220,240, 310,330, 371,380,390 I want to put these numbers into four buckets using range with value 40 for example. 0,1,2 are all in range 40. So they should be bucketed together 200,220,240 - same…
Capacytron
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Robots on the moon problem

One robot on the moon gathers resources to build more robots for 3 months, then he builds robots at the rate of one per month for two months and repeats the process. The robots made do the same thing. How long will it take for the population to grow…
Mario Tannous
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If I have a number $N$, what operation can I use to make a number $X^N$

I'm trying to create a method to a way to take a number and make it a part of another “family” of numbers. For example, given a number $X$, to make it a part of the family of even numbers, just multiply it by 2. Basically, I just want to take a…
Jon due
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Are there nonograms of odd dimensions with a strong property

This question is a follow on from the related question here. A nonogram (or griddler), for this purpose, is an $m\times n$ blank rectangular grid with clues for each row and column. A solution involves filling each square in the grid with a symbol…
Mark Bennet
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Math Ideas to Think About for Kids and Friends

What are some math concepts and stories that might make someone interested in mathematics? What are some math concepts that people can think about easily and find it interesting to think about? I want to try to get kids that I know to start to think…
user443408
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I want $2.5 million saved when I retire at 65. How much do I need to save every month to achieve this goal?

"Your goal is to retire at age 65 with $2.5 million in the bank. Imagine you are 25 years old. How much do you need to save every month between now an then if you can obtain the following returns on your investments: 4%, 6%, 8%, and 10%?" I just…
Carspn
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Why is the one's digit of the product of 6 consecutive positive whole numbers is always zero?

$0\cdot1\cdot2\cdot3\cdot4\cdot5 = 0$, but it works for any six consecutive whole numbers. What is the math behind this?
user3919652
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Finding a value between two numbers, given percentage, which is bigger when the percentage is smaller

I'd like to find a way to calculate a value which is between two numbers (100 - 500), and that gets smaller the more the percentage is bigger. This means that 100% should give you 100, while 1% should give you 500. How could I achieve this?
user9549355
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Generating a fixed number

I have a fixed number $a$. Now using $a$ I need to construct a number $b$ such that $0.99\leq b\leq 1$. Is there any mathematical formulation of such a construction that looks random. The generation of such a number should be deterministic. can…
Upstart
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What mathematically determines the price of a crytocurrency?

For those of you involved in crypto-currency, what mathematically explains the up's and down's of crypto-currency value? Such as the peaks and troughs one sees on crypto graphs. What might be the advantages of understanding the mathematics behind…
yre
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Calculating values based on different factors

First of all apologies, this is not a complex mathematical problem (I don't think) but I could not find any active math forums out there. I am having difficulties coming up with a formula. Lets say I am running a restaurant, and I have 3 employees.…
katie hudson
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$5$ divides $2ax+b$ for some integer $a$,given $5$ does not divide $x$

$x$ and $b$ are given.Let,$5$ does not divide $x$. Then $5$ divides $2ax+b$ for some integer $a$. How do i prove this? I have not gone through a course in number theory,so a general proof would be appreciated.
jimm
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"Names" of 2 dot-jumping puzzles

I'm sure I've come across 2 well-known recreational maths puzzles, both involving cells jumping over each other. Can anyone provide the relevant search terms? The first has an fully-infinite grid, divided in two by a horizontal line. Every point…
Brondahl
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Find the inverse ratio of a group of numbers.

(I'm very open to suggestions to a better title to my question) I have four numbers, 10, 20, 30 and 40. I need to multiply each of then by some number so that they are all equal. However the sum of the numbers I multiply by has to be equal to 1.000.…
Eyeslandic
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A drinking math problem

I've heard about this interesting cocktail - you get a mug of beer, you drink a sip and refill with vodka. Drink again and refill again. Repeat until there is only vodka in the mug. Then drink and refill with beer until it's only beer in the mug. So…
jivko
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