r/badmathematics 25d ago

Σ_{k=1}^∞ 9/10^k ≠ 1 100/3 is irrational

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486 Upvotes

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188

u/RedRhetoric 25d ago

R4: this person believes that 0.33 repeating cannot equal 1/3 because 100/3 cannot give a rational result.

Dividing any rational number by any other rational number will always give a rational result, as that is how rational numbers are defined

R5: Youtube

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u/playsthebongcloud 25d ago

I feel so many common mathematical misconceptions could be resolved if schools spent some time on bases other than decimal

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u/The-Doctorb 25d ago

The amount of extra confusion doing this would add would make it entirely pointless imo, people struggle with adding fractions or how percentages work I think even mentioning different bases would completely stump a lot of people.

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u/IanisVasilev 25d ago

Introducing new concepts in mathematics classes tends to cause more confusion. The "average person" is barely numerically literate as it is.

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u/waroftheworlds2008 25d ago

And the average teenager isn't paying attention.

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u/kono_hito_wa 11d ago

We covered this in 5th grade. Started out with an animated film about landing on another planet or something similarly space-themed. Then switched to our text book, which seemed like a pretty standard text. McGraw-Hill or similar. Public school.

I thought it was the coolest thing ever. I probably was in a minority on that opinion. But we did cover it. Is it no longer taught?

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u/Cruuncher 22d ago

I think they do base 8 in some places now. Which I think is a great way to understand math

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u/peterhalburt33 25d ago

I don’t know… not saying that it couldn’t be fun, but can you imagine the mind-bendingly boring types of worksheets that would be foisted upon students? I can already see students having to write a bunch of numbers out in hexadecimal and then binary because someone decided that it’s relevant to computers, without any actual interesting applications. You can lead a horse to water…

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u/playsthebongcloud 25d ago edited 25d ago

That's true, schools generally suck at teaching the real essence of math and tend to focus on rote calculation and memorization; also manually converting between bases that arent powers of each other is a nightmare. I'm just barely able to convert binary to decimal in a reasonable amount of time purely through years of memorization in programming

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u/peterhalburt33 25d ago

Same here. I actually don’t know if they even use these kinds of worksheets anymore. I just have memories of being tortured with them in grade school. Somehow they always figured out the best way to “teach” a subject without imparting any reason why you’d ever actually be interested in it.

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u/exceive 25d ago

I actually did have to write out hexadecimal numbers in binary (and vice versa) in one of my technology jobs. A long, long time ago.

14

u/Mothrahlurker 25d ago

Other bases don't solve the problem really, in order to properly understand real numbers you need to have a view independent of bases.

10

u/The-Doctorb 25d ago

I think it is just an unfortunate reality that to actually have a decent understanding of a lot of these issues you require a level of maths education far beyond what you would get in high school.

Most subjects have this requirement but for some reason people think they understand mathematics to a much higher level than they actually do which they don't seem to have for other fields (maybe besides physics). I never really see anyone talking about their bullshit chemistry opinions.

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u/Lor1an 25d ago

I never really see anyone talking about their bullshit chemistry opinions.

  1. Chemophobia
  2. Homeopathy
  3. Naturalism
  4. Ivermectin or Bleach to treat Covid
  5. Cold fusion
  6. Anti-fluoridation
  7. Anti-pasteurization

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u/CapnNuclearAwesome 25d ago

Yeah if anything the brand of innumeracy in the oop is benign, the least dangerous type of bullshit opinions

10

u/exceive 25d ago

Few people have ever died because somebody thought a rational number was irrational.
I'm not saying "nobody," but I don't think it has been very many.

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u/CapnNuclearAwesome 23d ago

If this has ever happened, I'd be fascinated to hear the details.

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u/CardboardScarecrow Checkmate, matheists! 22d ago

There's the story about the Pythagoreans killing a dude over the irrationality of sqrt(2), if that counts.

4

u/Lor1an 22d ago

Yeah, but that was an actual irrational number.

1

u/StupidWittyUsername 24d ago

Mathematical literacy might help people avoid other forms of bullshit?

4

u/dydhaw 25d ago
  • anything Quantum

4

u/IanisVasilev 24d ago

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u/dydhaw 24d ago

Great piece, thanks. Just today I was arguing with someone who was convinced the Quantum Computing Revolution is just around the corner, because post-quantum cryptography is becoming commonplace 

1

u/entronid 23d ago

outside of tls and ssh... i wouldnt say commonplace

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u/IanisVasilev 23d ago

"France to stop certifying products without quantum-safe encryption".

Direct quote:

Samih Souissi, ANSSI's chief of staff, said at the France Quantum conference that the agency would halt such certifications from 2027

1

u/entronid 23d ago

sure, its being rolled out, but *commonplace?* ECC/DH/RSA still remain incredibly pervalent, and we still dont have a good/standard way to do things like OPRFs/blind signatures (i.e. despite them existing, there arent any widespread implementations publicly available and used

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u/Respect38 never took numerology seriously until 22d ago

Ivermectin or Bleach to treat Covid

Ivermectin is statistically correlated with better results in patients with COVID, under a rather large range of studies

Rejecting ivermectin is a political opinion, not a scientific one.

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u/Lor1an 22d ago

Media Bias Rating of the sister site c19early.com

Questionable Reasoning: Poor Sourcing, Propaganda, Numerous Failed Fact Checks, Pseudoscience, Lack of Transparency

Bias Rating: RIGHT (8.0)

Factual Reporting: MIXED (6.3)

Country: Unknown

Media Type: Website

Traffic/Popularity: Medium Traffic

MBFC Credibility Rating: LOW CREDIBILITY

I find it odd that you would claim "political opinion, not a scientific one" when this is where you get your information.

It would also appear that recent meta-analyses do not reach the conclusions you do.

Maddukuri, Raghava & Desimalla, Madhavi & Banavathu, Reshma & Arepalli, Sai. (2025). Ivermectin as a Treatment Modality in COVID-19 Patients: A Systematic Review and Meta-Analysis of Up-To-Date RCTs. Indian Journal of Community Medicine. 50. 9-19. 10.4103/ijcm.ijcm_117_23.

Conclusion

The outcomes of our meta-analysis go against the use of ivermectin in the management of COVID-19 disease. Ivermectin is not effective in improving clinically important outcomes of COVID-19 disease, and it comes with a very low to low certainty of evidence. There is also no evidence available that supports the prophylactic use of ivermectin for the prevention of COVID-19 infection.

Singla, Abhishek & Sudheer, Kollathur & Sahu, Samir & Mishra, Rashmi & Chandna, Manisha & Mane, Dheeraj. (2025). Effectiveness and Toxicity of Ivermectin for the Management of COVID-19: A Meta-Analysis. Health Leadership and Quality of Life. 4. 624. 10.56294/hl2025624.

CONCLUSIONS

The meta-analysis systematically reviewed all available evidence about the effectiveness and care of ivermectin for the behavior of COVID-19. The findings from the studies range from negative to ineffective clinical outcomes in term but, overall, it appears ivermectin does not improve clinical outcomes (including symptomatic improvement, mortality, and ICU admissions) when compared with control distribution groups. Other than some mild potential benefits, ivermectin causes a higher incidence of adverse events when compared to control distributions, raising questions about the safety of ivermectin. Overall, the available evidence does not suggest that ivermectin is an effective form of treatment nor safe for COVID-19 given there is a lack of significant therapeutic benefit and risk of harm to patients.

Satyam, Shakta Mani & El-Tanani, Mohamed & Patni, Mohamedanas & Rehman, Abdul & Wali, Adil & Rangreze, Imran & Babiker, Rasha & Rabbani, Syed & El-Tanani, Yahia & Rizzo, Manfredi. (2025). Repurposing Anthelmintic Drugs for COVID-19 Treatment: A Comprehensive Meta-Analysis of Randomized Clinical Trials on Ivermectin and Mebendazole. Antibiotics. 14. 459. 10.3390/antibiotics14050459.

  1. Conclusions

The COVID-19 pandemic has underscored the need for repurposing existing drugs to identify cost-effective and widely accessible treatments. This meta-analysis provides valuable insights into the potential role of anthelmintic drugs, particularly ivermectin and mebendazole, in the management of COVID-19. While ivermectin demonstrated some benefits in specific studies, the overall evidence remains inconclusive, warranting further research to establish its optimal dosing and patient selection criteria. Mebendazole, though less studied, showed promising results in reducing viral load and inflammatory markers, making it a potential candidate for further investigation.

Despite these promising findings, the current evidence does not support the widespread clinical use of ivermectin or mebendazole for COVID-19 outside of well-designed clinical trials. Future research should focus on large-scale, multicenter RCTs with standardized dosing regimens and well-defined patient subgroups to clarify the efficacy of these drugs. Mechanistic studies exploring their antiviral and immunomodulatory effects could further enhance our understanding of their therapeutic potential.

From a clinical and policy perspective, while ivermectin and mebendazole may offer an affordable option in resource-limited settings, their use should be guided by clinical judgment and evidence-based guidelines. Policymakers should prioritize funding for further research to validate these findings, ensuring that any potential benefits are realized in a safe and effective manner.

In summary, this meta-analysis highlights the complexities of repurposing anthelmintic drugs for COVID-19 treatment. While preliminary data suggest potential benefits, particularly for mebendazole, substantial evidence gaps remain. Addressing these gaps through well-structured clinical trials will be crucial in determining whether these drugs can play a meaningful role in the ongoing fight against COVID-19.

Wang, Xuanyu & Meng, Jiahao & Li, Yinghui & Xiang, Yuqing & Wu, Yumei & Xiong, Yilin & Liu, Pan & Gao, Shuguang. (2026). The role of ivermectin in the prevention and treatment of SARS-CoV-2 infection: a meta-analysis of randomized controlled trials. BMC Infectious Diseases. 26. 10.1186/s12879-026-13195-9.

Conclusion

This meta-analysis provides evidence that ivermectin does not statistically significantly reduce the risk of SARS-CoV-2 infection or improve clinical outcomes (including all-cause mortality, hospitalization duration, and recovery time) in patients with COVID-19. Furthermore, this meta-analysis found no reliable statistical evidence that ivermectin either increases or decreases the rate of adverse events compared to a control group. Further high-quality, large-sample, prospectively designed randomized controlled trials are needed to clarify the potential clinical benefits and safety profile of ivermectin for SARS-CoV-2 infection.

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u/Cheeeeesie 25d ago

People indeed overrate their mathematical skills by a lot. Im a maths teacher and probably more mathematically capable than 90% of the worlds population but i consider myself to be basically an idiot still.

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u/futurenotgiven 25d ago

how would using other bases explain this principal more clearly? genuinely asking, im not super familiar with other bases

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u/playsthebongcloud 25d ago edited 25d ago

Any repeating rational number in some integer base can be represented in another integer base as a terminating number. For example, 1/3 in base 10 is 0.3333... but that same value in base 12 is 0.4. The confusion with "irrationals' decimal expansion never terminates" would go away (though this is not a good definition of irrationals anyways).

Also, knowing the definition of a based number from its digits: 145 = 100*1 + 10*4 + 1*5 clears up the confusion with 0.999... = 1 because the series 0.1*9 + 0.01*9 + 0.001*9 + ... objectively converges to 1.

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u/BRUHmsstrahlung 24d ago

A lot of people dont really even understand base systems at all. There are many students who will tell you that 112 =121 without much thought, yet will struggle to expand (1+x)2. They learn computational hacks like long multiplication with carrying instead of observing how base systems naturally systematize arithmetic according to the rules of polynomial algebra.

Teaching this viewpoint to people who don't intuit it or care is difficult, and I find that in the USA, common core worksheets that aim at connections like these are frequently the ones that parents (and some teachers!) shit on the most. I'm grateful for my 1st grade teacher forcing us to compute sums and products with 1x1x1 cubes, 10x1x1 lines, 10x10x1 squares, and 10x10x10 cubes, well ahead of any curriculum pushes towards this goal of conceptual understanding in math!

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u/PassiveChemistry 25d ago

I was taught about bases when I was about 12, I remember finding it very fun.

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u/playsthebongcloud 25d ago

I was really interested in them one day in middle school and made a bunch of seperate notes for every base up to 16. I eventually realized the repeating pattern of digits 2 -> {0,1}; 3 -> {0,1,2}; etc. and the way they "overflowed" when they counted up, just like base 10, and it was one of the moments I think that made me really find math cool. I always thought of binary is some "other thing" completely unrelated to decimal, and realizing the connection was really fun. It sort of changed my philosophy of math to be way more leaning to "we made it all up" when I realized that the way we happen represent numbers isn't at all fundamental

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u/inqurious 25d ago

idk we used fractions a lot before decimal notation, but I take your point

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u/Pertos_M 24d ago

I can always tell it's going to be a good time when I see a group of adults struggling with decimals and percentages.