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.

5128 questions
2
votes
4 answers

Please let me know why 2/16 has a remainder of 2. Thanks

I would like to know why this division 2/16 has a remainder of 2. I understand remainders from this division 10/6 = 1 remainder is 4. But I can't figure out why 2/16 has a remainder of 2. Thanks
Nata
  • 37
2
votes
0 answers

Infinite volume but finite surface area, in higher dimensions?

In Infinite Volume but Finite Surface Area a question is asked whether there is some shape in $\Bbb R^3$ that have an infinite volume, but a finite surface area, sort of the opposite of Gabriel's Horn. The answer seems to be that there is none, if…
Lennart - Slava Ukraini
  • 163
2
votes
0 answers

What are the fractal patterns produced by coloring according to digit sums of coordinates?

I recently encountered something odd and I was wondering if anyone have seen something like it before, and could possibly explain what is going on. Given a coordinate system, for each xy coordinate within that system apply some function f: f(x,y) =…
Atheuz
  • 43
2
votes
2 answers

Help me, was given a Mathematical problem to figure out, but the answers told me it was just demorgans law in c code.

Was given this to figure out. He said its mathematical, no its not homework. More of one guy trying to prove he is smarter than me. The code: (!(a&&b)) == |!a||!b| T !(a||b) == !a&&!b I think it might be some symbolic logic, but couldn't figure…
yiyi
  • 7,352
2
votes
0 answers

Find the nearest balanced integer

OEIS A036301 is a sequence of numbers $ n $ such that the sum of the even digits of $ n $ equals the sum of the odd digits of $ n $. Let's call these numbers "balanced". Given an input positive integer $ k $, I would like a procedure that finds the…
Hans Havermann
  • 51
2
votes
0 answers

How to adjust the curve of a sine wave formula?

Apologies to all I'm pretty ignorant to maths beyond high school level. Essentially what I want to do is create a sine wave that's a bit more curvy than just a standard sine wave (see image below) I'm using animation software and I can generate a…
champ
  • 21
2
votes
2 answers

Calculating with minimum values

I'm wondering if there is a mathematical solution to the following. I have a very simple formula of y=x*0,2. However, if x < 100 it should result in 20, if x > 100, it should result in x*0,2. Some examples: x=10, y should be 20 x=50, y should be…
ju5t
  • 23
2
votes
2 answers

Why does $11! - 10!$ equal $10!$ plus an extra digit in "ones"?

Pardon my English as I'm not a native speaker of the language and I'm not a big math guy, so please bear with me and my ignorance for a bit. I've unconsciously stumbled upon something that's most probably blatantly obvious and easy, yet I have no…
szychy
  • 139
2
votes
0 answers

Dates and times with no repeated digits?

I have a digital clock that shows the date and time like this: $$ \mathsf{YYYY-(M)M-(D)D\qquad (H)H:MM \; [:SS]} $$ That is, the seconds display is optional, and if the month or day or hour is single-digit, it won't display a leading zero. This is…
mjqxxxx
  • 41,358
2
votes
0 answers

Does the equation in Aphex Twin's "Equation" -song have any real resemblance?

Does the equation in Aphex Twin's "Equation" -song have any real resemblance? The song's title is: $$\Delta M_i^{i-1} = - \alpha \sum_{n=1}^N D_i[n]\bigg[ \sum_{j \in C[i]} F_{ji} [n-1] + F ext_i [n^{-1}] \bigg]$$ Intuitively, given the context,…
mavavilj
  • 7,270
2
votes
1 answer

How many one in a million people exist?

So if there are 7,632,819,325 people currently alive (According to google), then how many of those people are "One in a million"? My math behind it was to divide the number by a million, but I just wanted to double check. I got the number 7,632; as…
Gracie-Previelle
  • 29
2
votes
1 answer

Infinite hat problem error upper bound, in the case of seeing all other prisoners

The problem is from Infinite prisoners with hats -- is choice really needed? A countably infinite number of prisoners, each with an unknown and randomly assigned red or blue hat line up single file line. Each prisoner faces away from the beginning…
MaudPieTheRocktorate
  • 3,796
  • 16
  • 34
2
votes
3 answers

Pat the Mathemamagician Part 2

Sal the Magician asks you to pick any five cards from a standard deck. You do so, and then hand them to Sal’s assistant Pat. Then you pick one of the five cards, and Pat puts it back into the deck, and takes the remaining 4 cards, arranges them in…
fosho
  • 1,491
2
votes
2 answers

What is the maximum total displacement needed for sorting a list?

I imagined a system of $n$ "things" that are ordered: each "thing" has a specific place. Also, the $n$th thing is the last thing in the system, meaning that there is always a "thing" to which number $1$ is assigned. Given such a system, we can "mess…
God bless
  • 2,049
2
votes
1 answer

Transmit Two Numbers Using a Single Number

I am working with an industrial temperature controller, a PLC, and a limited number of numeric inputs. I have two channels on my temperature controller, each of which can generate an integer error code. Unfortunately, I only have one integer input…
Dan A.
  • 123
  • 4
1 2 3
…
35 36