493 reputation
313
bio website cobaltduck.info
location Milford, OH
age 42
visits member for 3 years, 8 months
seen 11 hours ago

A former math teacher for 10 years, converted to Software Engineering just a few years ago. Enjoy woodworking, kayaking, hiking, and geocaching.


Mar
19
comment Aunt and Uncle's fuel oil tank dip stick problem
@user135539: Do you have any links or other specifics of this publication, and the issue that contained your husband's problem? I would love to read and learn more about this, especially if you can lead me to the fabled and elusive solution "using only plain arithmetic" I have heard rumors about.
Oct
5
comment Why does my calculator show $2^{-329} = 0?$
Reminds me of this oldie but goodie: cs.bgu.ac.il/~omri/Humor/lightbulb.html (first item).
Sep
5
comment Why do you add +1 in counting test questions?
I first noticed this phenomenon in elementary school, where the baseball field's backstop had three sections of netting between four poles. I never knew this idea actually had a name, and was related to fences.
Aug
15
comment Is there a term for any number that is $2^n$?
This post on SO makes use of the term: stackoverflow.com/questions/9259952/…, so I'm not the only one calling it as such. Very curious that this got four down votes but was the OP's accepted answer.
Jul
26
comment Prove that the distance between a black and a white dot is one
One could exploit a technicality in that the question fails to define "one unit." Arbitrarily select one black point and one white point. Define the distance between these points to be one unit. QED.
Jul
20
comment Mathematical writing: why should we not use the phrase “we have that”?
If ever there was a case for being able to cross-list questions on multiple SEs, this is it. I think the English SE community would have as much to input about this as Math SE, and each would benefit from the other's insights.
Jun
20
comment How to solve a system of 2 equations in this form
This may also help you get started: en.wikipedia.org/wiki/Conic_section#Intersecting_two_conics
Jun
20
comment intersection of two graph
To put it simply, the graph of $f$ is a V shape, and each of the possible answers is a line. Choices A and B would look like $\underline{V}$, just with different amounts of space between the V and the underline, and choices C and D would look like V /, again just with different spacing between the V and the /. Only in choice E will the slash cut through the vee.
May
19
comment Why is 987654321/123456789 = 8.0000000729?
Unrelated, but ever notice that Sqrt(9.87654321) approximates pi? The number system is full of this kind of stuff.
May
12
comment How to represent the floor function using mathematical notation?
What do you mean by that big capital pi with all those other symbols around it? Can you describe that "without words" please? In your accepted answer, what does arctan mean? My point is, all notation was invented to describe some intellectual phenomenon, which may in turn have been based on some earlier idea, etc. until the whole thing ultimately boils down to cavemen telling how many mastadon had been successfully hunted by holding up fingers.
Apr
2
comment Is 1+1 =2 a theorem?
The fact that I can describe a system (such as the integers modulo 2) where 1 + 1 = 0, would seem to suggest your statement cannot be a theorem.
Mar
21
comment Is there such a thing as proof by example (not counter example)
As a teacher of mine once said: beware Merten's Conjecture! en.wikipedia.org/wiki/Mertens_conjecture
Mar
7
comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)
Or, more generally, that the ultimate result of this digital summing is the same as the remainder when dividing by 9.
Jan
23
comment “How I wish I could calculate pi” analogs…
Citation needed?
Dec
31
comment How to answer a student objection to the use of “of” in pronouncing f(x)?
joriki "would have told the student to keep up the critical thinking." However Ben Crowell responds "it's time to grow up to a more mature intellectual level." Very interesting.
Jun
22
comment Tuple definition
Have you checked the old stand-by for definitions? en.wikipedia.org/wiki/Tuple
Nov
16
comment Functions over $R$ such that $f(xy) = f(x)f(y)$
There is a term for what you are asking about, 'totally multiplicative function': en.wikipedia.org/wiki/Completely_multiplicative_function
Oct
17
comment Probability that Scouting ashes continue to circulate?
So if I am understanding you, a fire may have on the order $10^{26}$ atoms of ash at the end, and I remove about $10^{24}$ atoms. If I model this as a binomial with $n = 10^{24}$ and $p = .01$, then my expected number of atoms from the original fire is $10^{22}$. After two fires, this goes down to $10^{20}$ and so on, until by fire number 12, my expected value goes below $10^{0}$. Makes sense, if my interpretation is correct?
Oct
17
comment Probability that Scouting ashes continue to circulate?
@Didier Piau: en.wikipedia.org/wiki/Kolmogorov_zero-one_law (edited question accordingly).
Sep
23
comment How to answer a student objection to the use of “of” in pronouncing f(x)?
Andre: Perhaps this is why I no longer teach algebra, and am now a computer programmer! Greg: "When I make a word do a lot of work like that," said Humpty Dumpty, "I always pay it extra."