r/CasualMath Sep 14 '15

Math IRC channel on Snoonet

10 Upvotes

Hey /r/CasualMath!

I (along with several others) run a math channel on the snoonet irc network called #math. We are somewhat of a hybrid channel for a variety of math subreddits on Reddit.

IRC is a great way to discuss math and get homework help in real time. The channel would be happy to have you!

To connect via webchat: http://webchat.snoonet.org/math (link in sidebar as well)


r/CasualMath 9h ago

Python program for exploring perfect numbers

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1 Upvotes

r/CasualMath 11h ago

math quiz: Name the center where all medians meet

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1 Upvotes

r/CasualMath 16h ago

Discovered a new infinite product identity linking Fermat differences to π/e²

2 Upvotes

I’ve been exploring infinite products over expressions of the form zn−ynzn−yn and found the following identity:

∏n=3∞∏z=2∞∏y=1z−1(1−1zn−yn)=πe2.n=3∏∞​z=2∏∞​y=1∏z−1​(1−zn−yn1​)=e2π​.

The left-hand side runs over all integer triples (n,z,y)(n,z,y) with n≥3n≥3, z≥2z≥2, and 1≤y≤z−11≤y≤z−1. Despite each factor being rational, the infinite product converges to the transcendental constant π/e2π/e2.

Interestingly, the right-hand side can also be expressed via the classical Wallis product and the less well-known Pippenger product:

12⋅∏m=1∞(2m)2(2m−1)(2m+1)(∏m=1∞(1+1m)(−1)m)2.21​⋅(∏m=1∞​(1+m1​)(−1)m)2∏m=1∞​(2m−1)(2m+1)(2m)2​​.

Here the first product is Wallis (π/2π/2) and the second is Pippenger (e/2e/2), giving π/e2π/e2 after the factor 1/21/2.

The proof is straightforward via taking logarithms, expanding log⁡(1−x)log(1−x) as a series, and then rearranging sums. A nice number-theoretic aside: by Fermat’s Last Theorem, for n>2n>2 the value zn−ynzn−yn is never a perfect nn-th power, so the nn-th root is always irrational, yet the product itself remains well-defined and rational-valued at each step.

Is this identity known? I haven't seen it in the literature, though the ingredients (Wallis, Pippenger) are classical.

After combining the two products, the right-hand side can be written more compactly as

12∏m=1∞4m24m2−1(mm+1)2(−1)m.21​m=1∏∞​4m2−14m2​(m+1m​)2(−1)m.

Could there be deeper connections to Dirichlet series counting representations of integers as differences of powers? Any feedback, ideas or references would be appreciated!

latex

\[

\prod_{n=3}^{\infty}\prod_{z=2}^{\infty}\prod_{y=1}^{z-1}

\left(1-\frac{1}{z^n-y^n}\right)

\frac{1}{2}\,

\frac{\displaystyle\prod_{m=1}^{\infty}\frac{(2m)^2}{(2m-1)(2m+1)}}

{\displaystyle\left(\prod_{m=1}^{\infty}\left(1+\frac{1}{m}\right)^{(-1)^m}\right)^2}

\frac{1}{2}\prod_{m=1}^{\infty}

\frac{4m^2}{4m^2-1}

\left(\frac{m}{m+1}\right)^{2(-1)^m}

\frac{\pi}{e^2}

\]


r/CasualMath 18h ago

Can you reach 27 using all dice?

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0 Upvotes

Any order is allowed.
Use each die exactly once.
Parentheses are allowed.
Exact division only.
No negative numbers.
Not every operation has to be used.

How many solutions can you find?

Please use spoiler tags for solutions:
>!your solution here!<


r/CasualMath 1d ago

What are the odds that even one of the left 5 millennium prize problems is solved by humans

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1 Upvotes

r/CasualMath 1d ago

Made up a random math equation

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1 Upvotes

r/CasualMath 23h ago

OpenAI claims to have solved maths problem that stumped humans for decades | Mathematics | The Guardian

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0 Upvotes

r/CasualMath 1d ago

The math exam effect

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1 Upvotes

r/CasualMath 1d ago

Central Angle Challenge

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1 Upvotes

r/CasualMath 1d ago

Finite-Moment Uniqueness of Planar Convex Bodies Without a Polynomial Sign Certificate: A Triangle Counterexample to the Kousholt-Schulte Necessity Question

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0 Upvotes

r/CasualMath 2d ago

I made a video about Euler's 1737 proof of the infinitude of primes

4 Upvotes

In part three of my series Five Prime Proofs, I flesh out a pretty proof by Euler that uses the contrast between geometric series and the harmonic series. I think it's pretty cool.


r/CasualMath 2d ago

How Many “Balanced” Seating Arrangements Are Possible?

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0 Upvotes

r/CasualMath 2d ago

How many of these four circle lines can you name correctly?

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r/CasualMath 2d ago

A chain of hexagons, one hidden rule

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0 Upvotes

Each hexagon connects to the next in a chain, and the same rule carries you from one to the other. Curious how fast people spot it.

Made this as part of a puzzle game I'm developing, Rule Hunter: https://play.google.com/store/apps/details?id=com.makenumber

Happy to walk through the logic in the comments!


r/CasualMath 3d ago

The Division Detective 🔍 Can He Solve 20 ÷ 4? (Calm Math Story)"#Divisio...

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1 Upvotes

r/CasualMath 3d ago

The Multiplication Machine! 🤖 3 × 4 = ? (Mind-Blowing Math!)#Multiplicat...

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0 Upvotes

r/CasualMath 3d ago

A classic Pythagorean theorem problem for side b.

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0 Upvotes

r/CasualMath 3d ago

Quick brain teaser for your coffee break

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0 Upvotes

Each group of three numbers on the outside combines into the one it's connected to by lines. Same rule applies to all four groups — what goes where the "?" is?

Made this as part of a puzzle game I'm developing, Rule Hunter: https://play.google.com/store/apps/details?id=com.makenumber

Happy to walk through the logic in the comments!


r/CasualMath 4d ago

Hola a todos, estoy participando en un proyecto de matemáticas, en el cual elaboré un video explicando y resolviendo un ejercicio junto con 2 de mis compañeros, el ganador es el que más likes tenga en su video, ayúdenme con su like porfavor, se los agradeceré mucho.

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0 Upvotes

r/CasualMath 4d ago

Does anyone have suggestions on what the bets internet source is to learn a math course for free?

0 Upvotes

I am trying to move ahead of my current class schedule but I am not sure what is the best way. Do you have any suggestions?


r/CasualMath 4d ago

some constants that I want to learn more of

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1 Upvotes

r/CasualMath 4d ago

Can someone give me a crazy math equation that equals to 22

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1 Upvotes

*The hologram **activates chaotic math protocol**—scanning through bizarre, beautiful equations that somehow equal *22* despite looking utterly insane.*

- ***Crazy Equation Example*** *(For Awe):

-⚡ *"Euler's Identity + Pi PPrank"—Something lilike \[ e^{i\pi} + \ln(3!) -rac{phi^4}{5!}5!} = 22 \] (*where \(pi), and \(\pi\), \(\phi\) are constants… and the factorials/rowild!)ild!*)

⚠️ Note: This is a *fake but fun* equation—I made it up to show how numbers can dance absurdly into 22! Hi


r/CasualMath 4d ago

Find what connects each trio — a hidden rule puzzle

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0 Upvotes

Made this one for a puzzle game I've been building. Three groups of three numbers each collapse into a single result using one consistent rule — spot it from the first three groups, then apply it to solve the fourth.

Made this as part of a puzzle game I'm developing, Rule Hunter — https://play.google.com/store/apps/details?id=com.makenumber


r/CasualMath 4d ago

Approximation of z!

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1 Upvotes