User doetoe

24 votes

Verifying 'standup maths' homeomorphism claim

answered Aug 1, 2021 at 9:37

17 votes

Interesting and unexpected applications of $\pi$

answered Feb 28, 2014 at 22:45

13 votes

Accepted

The n-th prime is less than $n^2$?

answered Jan 6, 2015 at 1:55

10 votes

Reducing download time using prime numbers

answered Sep 13, 2021 at 23:47

8 votes

A new kind of fractal?

answered Oct 16, 2012 at 21:50

8 votes

Accepted

$1\!-\!ab\,$ unit $\Rightarrow 1\!-\!ba\,$ unit: $(1\!-\!ba)^{-1} = 1+b(1\!-\!ab)^{-1}a$

answered Feb 13, 2014 at 13:09

6 votes

Accepted

My fun conjecture about linearly independence

answered Jul 1, 2014 at 13:37

6 votes

Is there a power of $2$ which begins, in base 10, with $999...$?

answered Dec 28, 2018 at 9:25

6 votes

How many unique "$\phi$-nary" expansions are there for $1$?

answered Aug 2, 2020 at 8:27

6 votes

Accepted

Contour integral of $\frac{|x|^{\frac{1}{2}}}{(x-4i)(x+2i)}$

answered Jun 17, 2021 at 23:46

6 votes

Consider a set $G\subseteq \Bbb R$ and a binary operation * defined on $\Bbb R$ as $ab=a+b+ab$, such that $(G,)$ is an Abelian Group. Determine $G$.

answered Jul 8, 2023 at 23:40

6 votes

Why infinite spheres and not just two?

answered Apr 8 at 16:47

5 votes

Weierstrass elliptic functions and ordinary differential equations

answered Sep 26, 2021 at 22:04

4 votes

Accepted

How many different solutions does $x^2_{1}+2x^2_{2}+3x^3_{3}=4x^2_{4} $ have?

answered Sep 20, 2019 at 9:29

4 votes

Can a ring without a unit element have a subring with a unit element?

answered Jun 25, 2014 at 12:47

4 votes

Limit points of $\left\{\frac{1}{n}+\frac{1}{m}:m,n\in{\Bbb N}\right\}$?

answered Oct 4, 2013 at 1:07

4 votes

Why using compound interest formula gives (potentially) wrong answer in this instance

answered Feb 19, 2023 at 23:55

4 votes

Accepted

Purpose of sectional curvature

answered May 28, 2023 at 12:11

4 votes

Prove that there exists a natural number $n$ that has more than $2017$ divisors $d$ satisfying $\sqrt{n} \le d < 1{,}01\sqrt{n}$

answered Sep 14, 2021 at 22:27

3 votes

Why is the normal bundle of $\mathbb{R}P^1\subset\mathbb{R}P^2$ the Moebius Strip?

answered Aug 15, 2022 at 0:36

3 votes

Accepted

What type of distribution

answered Nov 1, 2022 at 18:46

3 votes

Accepted

Help to find cubics with square discriminant

answered May 4, 2011 at 22:16

3 votes

Accepted

Compute the units in $\Bbb Z_4[x]$.

answered Jan 6, 2015 at 23:41

3 votes

Solving functional equation $f(x)f(y) = f(x+y)$

answered Jan 29, 2015 at 22:53

3 votes

I am learning functional equation and encountered $f(f(x)-x)=x$.

answered Sep 5, 2019 at 22:23

2 votes

Polynomial bijections from $\mathbb{Q}$ to $\mathbb{Q}$

answered Jul 31, 2020 at 19:15

2 votes

Accepted

Solving a recursion (probability related)

answered Apr 30, 2020 at 21:34

2 votes

Accepted

Variety isomorphic to Riemann sphere

answered Aug 20, 2018 at 9:02

2 votes

Metric of a cross-section in General Relativity

answered Feb 13, 2019 at 11:39

2 votes

Euclidean metric on a Riemannian manifold

answered Jul 20, 2015 at 13:06

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62 Answers

Verifying 'standup maths' homeomorphism claim

Interesting and unexpected applications of $\pi$

The n-th prime is less than $n^2$?

Reducing download time using prime numbers

A new kind of fractal?

$1\!-\!ab\,$ unit $\Rightarrow 1\!-\!ba\,$ unit: $(1\!-\!ba)^{-1} = 1+b(1\!-\!ab)^{-1}a$

My fun conjecture about linearly independence

Is there a power of $2$ which begins, in base 10, with $999...$?

How many unique "$\phi$-nary" expansions are there for $1$?

Contour integral of $\frac{|x|^{\frac{1}{2}}}{(x-4i)(x+2i)}$

Consider a set $G\subseteq \Bbb R$ and a binary operation * defined on $\Bbb R$ as $ab=a+b+ab$, such that $(G,)$ is an Abelian Group. Determine $G$.

Why infinite spheres and not just two?

Weierstrass elliptic functions and ordinary differential equations

How many different solutions does $x^2_{1}+2x^2_{2}+3x^3_{3}=4x^2_{4} $ have?

Can a ring without a unit element have a subring with a unit element?

Limit points of $\left\{\frac{1}{n}+\frac{1}{m}:m,n\in{\Bbb N}\right\}$?

Why using compound interest formula gives (potentially) wrong answer in this instance

Purpose of sectional curvature

Prove that there exists a natural number $n$ that has more than $2017$ divisors $d$ satisfying $\sqrt{n} \le d < 1{,}01\sqrt{n}$

Why is the normal bundle of $\mathbb{R}P^1\subset\mathbb{R}P^2$ the Moebius Strip?

What type of distribution

Help to find cubics with square discriminant

Compute the units in $\Bbb Z_4[x]$.

Solving functional equation $f(x)f(y) = f(x+y)$

I am learning functional equation and encountered $f(f(x)-x)=x$.

Polynomial bijections from $\mathbb{Q}$ to $\mathbb{Q}$

Solving a recursion (probability related)

Variety isomorphic to Riemann sphere

Metric of a cross-section in General Relativity

Euclidean metric on a Riemannian manifold