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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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making integers from a given set

this Q is very easily generalizable. For example consider $1,2,3$ and $4$. We have $1=1, 2=2, 3=3, 4=4, 5=4+1, 6=2\times 3, 11=4\times 3-1$. You can only use each number once. 37 is the first number not achievable. Does 1,2,3,4 form an optimal…
JMP
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Find least numerator and denominator for a given sequence of numbers in decimal form

Say I have a sequence (s) of digits written as number. (Ex: 1234567890) I need to find out shortest possible pair of numerator (n) and denominator (d) that ,being converted to decimal form of fraction (r), starts with that sequence after a decimal…
Lex Podgorny
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If I hear thunder 5 seconds after I see the lighting, can I calculate the distance to where lighting occurred?

My kid asked me this the other day, and it got me thinking that it is really impossible to calculate. We know the speed of sound (340.29 m/s) and speed of light (299,792,458 m/s) and I can calculate the offset of how far it travelled in 5…
AngryHacker
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Determining Formula (Game Mechanics)

WARNING I believe that the data below has errors in the defense strength, so is therefore not solvable. I will update it when I have more information. Thank you. I play a game (Empire: Four Kingdoms) in which soldiers attack castles where other…
lnafziger
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Why is the three utility problem important?

I came across this problem on this website, even though it was fun to answer it there was something sad I realized, and I wanted to ask this from the Math Stack Exchange community. The question: Connecting three houses to three utilities To me…
user181306
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Are there tricks to solve seating arrangement problems?

How are seating problems solved in general? I am stuck on this one for example. There are 8 houses in a line and in each house only one boy lives with the conditions as given below: Jack is not the neighbour Siman. Harry is just next to the left of…
user1502
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Mathematical reasons for hull design relative to sustainable angle of heel

I've recently been doing a comparative study of ancient Sumerian mythology relative to the book of Genesis. I am curious if there is a way to explain mathematically why a circular, square (cubic) or rectangular boat might be more or less viable than…
123
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what is the formula for determining the next year in which a given month/day will occur on a specific weekday

So, I was trying to express the formula for determining the next year on which a given date (month/day) will fall on a given weekday. The internet has plenty of sites that explain how to determine the weekday of an arbitrary date (at least up…
Robert
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How many times can you round a number?

For a typical rounding algorithm, I'm wondering how long the rounding chain goes for when you round up a number. For example, if you have a decimal like 0.4445, you round the last 5 up, which would round it to 0.4450, which would round it to…
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Two Genius Mathematicians

This is actually a question I find really hard to answer.any hints are appreciated. By the way feel free to edit the tags as i really do not know which category is this question is in. Two genius mathematician have guessed two numbers which their…
Minuano
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find the sales tax from a tax included price that does NOT apply tax to the portion of the total that IS tax

I, a vendor, need to find the sales tax from a tax included price that does NOT apply tax to the portion of the total that IS tax. Most answers result in overpayment of taxes. Please do not tell me this: receipts from items subject to sales tax,…
user3648099
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Solving math word problems WITHOUT brute force

How can we solve these problems withing using brute force? http://edhelper.com/math/multiplication51.htm
foodals
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Continue the sequence

I'm stack at that question as I'm not sure which law does the sequence obey What number comes next in this series: 1 11 21 1211 111221 312211 13112221: 12113331 1113213211 13221113 113211321
S.D.
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Is it possible to reach 50k in the game 2048 with only having a highest tile of 512?

Is it possible to reach a score of 50,000 in the game 2048 with only having a highest tile of 512(Only one 512 was present) and one 256 tile and other small numbered tiles such as 2,4,8,16,...,64. Because my friend has done so in her phone and I am…
user3436836
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Which performance enhancement is better?

Suppose you are given the task of improving the performance of a program consisting of three parts. Part $A$ requires 20% of the overall run time, part $B$ requires 30%, and part $C$ requires 50%. You determine that for \$1000 you could either speed…
mharris7190
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