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bio	website	jstuber.net
	location	North Rhine-Westphalia, Germany
	age	48
visits	member for	2 years, 10 months
	seen	Jan 13 at 11:48
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I'm a free-lance embedded software developer who likes computer science, mathematics, electronics and foreign languages.

e^iπ + 1 = 0

e^π√163 ≅ 640320³ + 744

rot13("fr") = "se"

	286 reputation	bio	website	jstuber.net	visits	member for	2 years, 10 months
17 badges		location	North Rhine-Westphalia, Germany		seen	Jan 13 at 11:48

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Aug 6	awarded	Nice Answer
Oct 23	comment	Integral solutions of $x^2+y^2+1=z^2$ You are not trying to solve Project Euler problem 224, are you? projecteuler.net/problem=224
Oct 9	comment	Why is it called a 'ring', why is it called a 'field'? And it is still "Körper" in German.
Oct 3	comment	How to derive a function to approximate $\sqrt{3}$? It is much older than Newton's method: en.wikipedia.org/wiki/…
Sep 12	comment	Mathematical operation with unique result These are of course ordered pairs, edited to make that explicit.
Sep 12	revised	Mathematical operation with unique result added 8 characters in body
Sep 9	answered	Mathematical operation with unique result
Sep 9	comment	In set theory, how are real numbers represented as sets? You have to exclude at least <0,0> in the construction of Q. It would be related to all other pairs so transitivity would fail.
Aug 31	comment	What is the result of infinity minus infinity? This infinity of a denumerable set of things is normally written ω (omega), it is the least infinite ordinal (there are many many more infinite ordinals).
Aug 26	comment	Who invented $\vee$ and $\wedge$, $\forall$ and $\exists$? They also had funny names as mnemoics for their inference rules, such as Barbara, Celarent, etc, where the vowels encoded the sentence forms.
Jul 28	awarded	Yearling
Jul 24	comment	Real world applications of Pythagoras' Theorem Please list what you already have.
Jul 20	comment	divisibility of ABCD+DCBA by 11 For an odd number of digits the middle digit will lead to a summand `2 * d * 10^k`, so it can only work for divisibility by multiples of 2 and/or 5.
Jul 14	answered	Are all numbers real numbers?
Jul 14	comment	Are all numbers real numbers? The rationals don't have gaps, they are dense.
Jun 19	comment	Finding the 10001th Prime @Luboš Please delete your comment, it is a spoiler for those who still want to solve the problem.
Jun 18	answered	Proof that cube has 24 rotational symmetries
Jun 17	comment	How to build up the congruence equation? (x+1) is to accommodate our human way of counting starting at 1.
Jun 15	comment	A curve that starts with exponential growth and levels out You say "starts out with exponential growth", so you want the logistic function.
Jun 13	comment	What is a null set? Note that these are different ways to write down the empty set. There is only one due to extensionality.