/r/CasualMath
This is a subreddit that is meant to be somewhere inbetween /r/math and /r/learnmath.
This is a subreddit that is meant to be somewhere inbetween /r/math and /r/learnmath.
It is my hope that crummy mathematicians can discuss old ideas and prove old theorems and solve old puzzles here. Just because someone did it before doesn't mean we can't have fun with it, right?
This is a place where things like the Ulam Spiral and prime-rich polynomials are tolerated as reposts.
Please do use freely available resources where possible. Some crummy mathematicians aren't as fortunate as you are :)
This is our wiki and we encourage contributions of any sort, especially if they're interesting.
Post Spoilers in this format
[X proves Y!](/spoiler)
It will show up like this:
X proves Y!
Using LaTeX
To view LaTeX on reddit, install one of the following:
MathJax Greasemonkey userscript
TeXtheWorld Chrome extension
TeXtheWorld Greasemonkey userscript
[; e^{\pi i} + 1 = 0 ;]
Post the equation above like this:
`[; e^{\pi i} + 1 = 0 ;]`
You may need to add four spaces before or put backticks around math fragments.
Using Superscripts and Subscripts
x*_sub_* makes xsub
x*`sup`* and x^(sup) both make xsup
x*_sub_`sup`* makes xsubsup
Related Subreddits:
IRC channel:
Discord servers:
/r/CasualMath
14,976 Subscribers
New proof (as far as I'm aware) 0.999... = 1
0.999... + 0.111...
= (0.9 + 0.09 + 0.009 + ...) + (0.1 + 0.01 + 0.001 + ...)
= 0.9 + 0.1 + 0.09 + 0.01 + 0.009 + 0.001 + ...
= (0.9 + 0.1) + (0.09 + 0.01) + (0.009 + 0.001) + ...
= 1 + 0.1 + 0.01+ 0.001 + ...
= 1.111...
= 1 + 1/9,
therefore 0.999... + 1/9 = 1 + 1/9. Subtract 1/9 from both sides, then 0.999... = 1.
03:34 UTC
Problem given to elementary school children in China.
20:49 UTC
Partial Limits and Generalized Limits
19:15 UTC
Determine the area of a given triangle based on the provided conditions or dimen
Point C is on line segment AB, where AB = 6 and AC = 4.
An equilateral triangle CEG is formed with C as one of its vertices.
Lines AE and BG are drawn.
When the sum of AE + BG is minimized, find the area of triangle CEG.
11:32 UTC
Does a random 3-digit number have the same chance of resulting in any number from 1-100 if adding the front 2 and back 2 digits together and over 100 subtracting 100?
For instance, 443 = 44+43=87
822 = 82+22=104=4
099 = 9+99=108=8
130+13+30=43
If that makes any sense
So far, I have gotten these numbers: 4 7 8 9 13 14 16 19 21 24 43 45 49 51 68 71 80 84 87 87 89 96 96
I am not a student, just curious.
05:12 UTC
An interesting geometry problem with a simple solution
23:46 UTC
Visual Trigonometry
Dear Members and Moderators.
Please ignore if this is not the right way to get started here.
I want to share https://visualtrigonometry.com/ with the group here. A VISUAL WAY to calculate sin, cos, tan, etc. (Trigonometric Calculators) and arcsin, arccos, arctan, etc. (Inverse Trigonometric Calculators) for the community's use; especially students.
Any critical feedback is welcome!
Regards,
Swapneel Shah
03:08 UTC
Math Competition Tutoring Opportunity - CompetifyPlus
CompetifyHub is happy to announce the next level in the Competify family: CompetifyPlus (https://competifyplus.com/)
CompetifyPlus provides affordable competition math tutoring,. The link to join as a tutor: https://form.jotform.com/243234411204138
Why Join Us:
High Impact: the competify family has partnered with over half a dozen competitions and share resources to over 4,000 people monthly, allowing for quick growth.$Money$: Tutors keep 70% of the income from their classes, with the rest spent on organizational fees and other expenses.
Skills: Explaining ideas is a crucial skill, and building that skill while making bank is quite the value.Low maintenance (classes align with your timings)- highly rewarding
Feel free to reach out (Direct message me) with any questions!
14:24 UTC
A quick probability problem for anyone interested
08:49 UTC
Math Exercise App available on Google Play Store
We are now available on Google Play Store.
You can find zero to hero math exercises including Arithmetic to Calculus and Linear algebra
You can download on
https://play.google.com/store/apps/details?id=com.entusia.entusia
Enjoy
20:15 UTC
Best Exam preparation Lecture-notes on Linear Algebra
15:25 UTC
Thanksgiving Mental Math Fun Tournament
Hey everyone! We're hosting a Thanksgiving Arithmetic Dash over the next nine days. This is a three-minute speed-based math contest consisting of simple arithmetic questions - and we will be awarding certificates to the top 10% of participants in each country, state (if US), and age group.
We hope it is fun, and a cool way to compete against others from your country, state, or age!
The contest is here: https://mathdash.com/contest/thanksgiving-arithmetic
We also recommend that you participate in the practice contest beforehand in order to get a feel for the format - the practice contest is here: https://mathdash.com/contest/thanksgiving-arithmetic-practice
Good luck!
03:05 UTC
Tetris-Inspired Math Game
I've always thought that practicing mental math could be more engaging, so I decided to build a simple game that combines the fun of classic Tetris with quick math challenges. In the game, numbers fall from the top, and you have to solve the math problems before they hit the bottom.
It's designed to help improve fast counting and mental calculation skills in a fun way. If you're interested in giving it a try, here are the links: Android and iOS
I’d love to hear your thoughts and any feedback you might have!
11:56 UTC
Challenge - Find Surface Area
01:17 UTC
equ8
Hey everyone! I made a game called equ8 (“equate”). You’re given four numbers, standard operators, and a target number, and the goal is to create as many equations as possible to equal the target number. For each correct equation, you get points and level up. You can share your score and compete with your friends.
Check it out at https://playequ8.com
Let me know what you think!
18:43 UTC
List off functions whose infinite sum of derivatives converge.
As the title says, I would like you all to suggest some continuous functions whose infinite sum of derivatives (f(x) + f’(x) + f’’(x) + …) converges for at least one value of x. I came up with a representation that evaluates this and I wanted to test it with continuous and infinitely differentiable functions.
I came up with a few, like polynomials and exponential functions but some other people’s ideas are beneficial.
22:35 UTC
Visualized Proof of the Bolzano-Weierstrass Theorem using Cantor's lemma
21:18 UTC
Slot Machine Question. Hitting the same pattern two times in a row. 3x5. Does anyone know the answer?
Hello, i am wondering what the odds are to hit the same exact pattern on a 3 by 5 (3 rows, 5 columns) slot machine.
Say this is the slot:
(row 1)X X X X X (row 2)X X X X X (row 3)X X X X X
x=represents the symbols and/or numbers
Also, they’re 11 symbols/numbers.
can anyone tell me the probability or if this is even possible?
04:09 UTC