r/CasualMath • u/caiobzen • 21m ago
r/CasualMath • u/mangopear • Sep 14 '15
Math IRC channel on Snoonet
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 • u/Western-Rush878 • 6h ago
Need help with analyzing certain mathematical claims being made. Is this an instance of data manipulation and bias on my part, or something is actually going on here?
Can anyone here please take a look at some of the claims made by Ali Fazely on the supposed mathematical miracles linked to the number 19 of the Quran, especially using prime and composite numbers? I genuinely don't even know what to think at this point
For example (and this is both used as evidence for the removal of Quran 9:128-129 as well as trying to demonstrate the nature of the supposed divine code of the number 19 in this book):
The number of verses in the Quran from 1:1 until 19:98 (since it's part of the whole code 19 stuff) is 2346 (not including 9:128-129). The factors of 2346 are 23x2x3x17 which have the prime indices of 9127 similar to Quran 9:127 being the cutoff point as proposed by Rashad Khalifa (the person who developed this whole idea of the Quran being shaped around this number 19 in the first place). Finally if you place the digits 2346 in a permutation table, the 19th permutation is 6234, the total number of verses in the quran if you remove 9:128-129.
Link to the book here, starting on page 44: https://pdfcoffee.com/the-ultimate-mathematics-of-the-quran-pdf-free.html
I don't understand how this is happening, since it's one thing if he only used this method once selectively, but he continues to use it similarly over and over. Wanting to understand whether or not there is more to this, or it's simply pattern recongition and being able to use many numbers at hand.
If someone could take some time out of their day to analyze some of the claims being made and techniques being used, it would truly mean the world to me. This stuff has been stressing me out and I'd like someone who can objectively and non-biasedly look at the following and help me out with it.
r/CasualMath • u/Lubitelb_Dobra • 7h ago
Математик
Всем привет, сегодня пришел с вопросом о математике который говорил о этажах изучений, я думаю все знают о 7 по-моему нерешаемых примерах которые пока что невозможно решить, и был современный ученый который сказал «что бы решить этот пример нужен 5 этаж математики» не помню как его зовут, подскажите пожалуйста🙏
r/CasualMath • u/Fergus4535 • 12h ago
Whats the formula to calculate how much you need to make in order to have the same amount after a percentage is deducted?
I think there is one but ive not had to use it for like 5 years so ive completely forgotten it. To explain further:
I have X, i need Y to sustain X. Y costs a percentage of the growth of X.
So
X doubles annually (also, please help me with this- i dont remember the formula which is shorter for A x 2 x 2 x 2 x 2 x 2 etc)
Y costs 1/5 of X's growth on top of the previous year
I want to make back Y through X but also the cost grows with the more of X i have.
r/CasualMath • u/Accomplished_Ant5859 • 16h ago
Digit vs. Value Made Easy! 🦖 Hundreds, Tens & Ones | DinoMath Place Value
youtube.comr/CasualMath • u/EconomyBox6998 • 20h ago
I love generalization.
galleryIn the last post, i showed a generalized Formula for converting natural-decimal numbers into any base-b system like binary (base-2). (**I'm gonna focus on base-2)**
But the mathematical structure of it required us to compute something like this:
If m = 16, we will have this as a result:
bas_2(m) = 10⁴(1)+10³(0)+10²(0)+10¹(0)+10⁰(0) = 10000
Looking at it, there are powers of 10 that multiplied by (0), it would be easy if we have just the powers of 10 that are multiplied by (1) and then add them up.
Let m = 5, in base-2 = 101, or we can also write that
m = 2²(1)+2¹(0)+2⁰(1) = 5
If we look closely, only two powers of 2 make up to 5
If m = 10, only two powers of 2 needed (1010)
If m = 13, only three powers of 2 needed (1101)
If m = 16, only one power of 2 is needed (10000).
The ( how many powers of 10 we need ) or the (upper bound of the sum) depends on how many 1s in a base-2 representation of a number (m).
Hence the function bi_1(m), this function i made (based on Legendre's formula) counts how many 1s in a base-2 representation of a number (m). That is gonna be the upper bound of the sum.
The next part is what powers to raise 10 after removing all powers of 10 that multiplied by (0)?
First i defined e_i = floor(log_2(m_i)
This function takes the power of (m) from its equal value when m = 2\^a, and lowers that (a) down to a clean integer.
Like m_1 = m = 5, m = 2\^a where 2 < a < 3 (a here is not an integer ), so e_1= floor(a\*log_2(2)) = b were b = 2 in our case of m = 5.
The value of e_i has powers of 2 that are multiplied by 1 only, let m_1 = m = 25, e_1 = floor(log_2(25)) = 4
m_2 = 25 mod 2\^e_1 or 25 mod 2⁴ = 9
e_2 = floor(log_2(9)) = 3, m_3 = 25 mod 2\^e_2 = 1
e_3 = floor(log_2(1)) = 0, m_4 = 25 mod 2\^e_3 = 0
Until we hit zero, the values of e_i are the ones needed to raise as a powers for 10 because they bypass all powers of 2 that multiplied by (0) like in 25 in binary 11001
m = 25 = 2⁴(1)+2³(1)+2²(0)+2¹(0)+2⁰(1)
The values e_1 = 4 in 2⁴, e_2 = 3 in 2³, e_3 = 0 in 2⁰, e_i takes the powers of 2 needed and bypass any powers of 2 times (0).
So we raise 10 to there powers to bypass multipling by (0), which means 10\^e_i.
And we just put everything together now and we get the formula that gives only the needed powers of 10.
In the next post i will show you all the general formula for any base-b after reconstruction it math structure.
r/CasualMath • u/Karl_Schraubhuber • 1d ago
The Miracle of St. Gallus and the Black Forest Fox (A math fairy tale puzzle)
Hello everyone! Here is a little puzzle for you:
Once upon a time, deep in the Bavarian Forest, lived an old farmer's wife with 7 hens.
The laying performance of her hens varied greatly. Her 1st hen laid an egg every day, her 2nd hen laid an egg every 2nd day, and this pattern continued all the way to her 7th hen, which only laid an egg every 7th day.
She sold every single egg for 20 Pfennige (100 Pfennige = 1 Mark).
On St. Gallus Day (October 16th) in a leap year—the patron saint of all chickens—a miracle occurred: all 7 hens laid an egg on the exact same day!
The Question: How much money did she make from that day up until the next day this miracle repeated itself for the remaining flock? (Note: The eggs from both miracle days are included in the earnings). The Incident: On Christmas Eve (December 24th), a fox broke into the coop and stole the 4th hen!
r/CasualMath • u/Otherwise_Strike_597 • 18h ago
Grade 9 Math: Calculate a 25% Down Payment on $600K
r/CasualMath • u/ZoranRajkov • 1d ago
Number pattern puzzle — find the hidden rule
Original number pattern puzzle I made — find the hidden rule connecting the pairs and figure out what's missing (see image).
Answer/reasoning in comments if anyone wants to discuss!
Source: made this myself for a puzzle game I'm developing, Rule Hunter — https://play.google.com/store/apps/details?id=com.makenumber
r/CasualMath • u/Karl_Schraubhuber • 1d ago
The Birthday Paradox v2.1 (featuring Arnold Schwarzenegger & Marie Curie)
Hello everyone!
The challenge: How many people must enter a room for there to be a 50% probability that at least two women share the same birthday?
The following conditions apply:
Condition 1: It is a leap year, and only adults may enter.
Condition 2: Exactly 10% of the world's population are twins. (They would enter individually.)
Condition 3: The seventh person to enter the room is Arnold Schwarzenegger.
Condition 4: The next person to enter the room is Marie Curie, who we know was born on November 7th.
r/CasualMath • u/Far_Moment_6675 • 2d ago
Math Alarm – Solve to Wake Up
galleryI'd like to introduce my little free Android app for math enthusiasts: *Math Alarm – Solve to Wake Up*. If you have trouble getting out of bed and math is your passion, this app is for you. In your free time—or before an exam—you can use the "Exercises" tab to exercise your brain, or the "Dice" tab for random problems. The app also has a built-in step-by-step math problem solver, so you can use it if you're stuck on a specific question. I recently added a "Daily Challenges" tab with a timer where you can challenge yourself in your math skills. If you want to try it out, here's the link: https://play.google.com/store/apps/details?id=com.wojtek.example.math_alarm&pcampaignid=web_share or on my blog: https://mojeaplikacja.blogspot.com/2026/06/math-alarm-wake-up-with-your-brain-on.html
r/CasualMath • u/Effective-Dish-1334 • 2d ago
this is the reason your clock divides hour into 60 minutes is because Sumerian and Babylonian astronomers counted finger knuckles instead of whole fingers
thehistoricalinsights.pager/CasualMath • u/IngenuityNo8548 • 2d ago
When should a parent consider getting a math tutor?
r/CasualMath • u/ZoranRajkov • 2d ago
Made a mobile puzzle game around finding hidden rules — here's one example, can you crack it?
galleryI've been building a puzzle game called Rule Hunter — each level gives you a
few example pairs and you have to figure out the hidden rule connecting them,
then apply it to solve the final case.
Here's one from the Normal difficulty:
3 → 9
5 → 25
8 → 64
7 → ?
What's the rule, and what's the answer?
(It's a free Android game, link in comments if anyone's curious — didn't want
to make this feel like an ad post.)
r/CasualMath • u/Advanced_Law4553 • 2d ago
I built an AI math solver that solves problems fro
r/CasualMath • u/Echo_Vale • 4d ago
£1 for a 1/10,000 chance? I like those odds!
4 digits, 0-9. I was volunteering at an animal charity stall the other day, the lovely lady who put this together thought it was a great idea and she genuinely hoped someone would win it. No one did. I didn't have the heart to tell her the actual odds.
r/CasualMath • u/Otherwise_Strike_597 • 3d ago
Can you solve this mean, median, mode, and range challenge?
r/CasualMath • u/Parallel_thougts • 4d ago
I made a video about Goldbach's 1730 proof that there are infinitely many primes
youtube.comSecond episode of a five part series, each about a different proof
r/CasualMath • u/Aware-Climate1010 • 4d ago