Dan Neely
Reputation
292
Top tag
Next privilege 500 Rep.
Access review queues
 May 6 comment Prove by mathematical induction that $1 + 1/4 +\ldots + 1/4^n \to 4/3$ @GitGud mathematicians, or people who saw the question in the hot question dropdown and voted for the answer with a pretty picture that they thought they understood? May 2 comment Repeating Decimals I normally demonstrate this technique by subtracting 100x from 10000x instead. Functionally they're equivalent; but making the decimal part go away completely in a single step seems to result in more people getting the concept immediately. Apr 26 comment Why is every answer of $5^k - 2^k$ divisible by 3? @SalvadorDali I think you're worrying too much; the same happens everywhere and the huge numbers of upvotes for questions asking "something every programmer should know" certainly hasn't kept stackoverflow itself from becoming one of the top programming help sites. If you're really concerned though, I suggest taking the issue from here to Meta.SE since its a network wide phenomena. Apr 26 comment Why is every answer of $5^k - 2^k$ divisible by 3? @SalvadorDali that happens all over on SE; some simpler questions get lots of upvotes from people who understand the subject matter well enough to say "hey that's neat"; but who ignore questions that they don't understand well enough to vote on. Once a question gets voted onto the hot question dropdown it's going to be seen by a huge number of people most of whom don't know math beyond basic calculus and whose voting will swamp that of the mathematicians who frequent this site. Mar 22 comment How did Euler prove the Mersenne number $2^{31}-1$ is a prime so early in history? @user13107 French Mar 12 comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book) @Ben That was the only argument that I was willing to accept prior to learning calculus and having my assumptions about infinitesimals corrected. Mar 7 comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book) There are simpler fractals that are simple enough for a child to understand conceptually that still produce pretty pictures. ex en.wikipedia.org/wiki/Barnsley_fern Feb 21 awarded Notable Question Feb 20 comment Is it true that the book 'Calculate Primes' has found the pattern? @user58512 Chakra has been active at a low level on Stack Exchange for four years. The book might be without merit; but I find it very unlikely that the author would have created an account 4 years ago to promote a book now. Feb 14 awarded Critic Feb 6 comment Solving 4 unknown angles in quadrilateral possible? @nbubis larger buildings anyway. Aside from the roof and supports for a flight of stairs, framed houses are almost entirely built from rectangles. Feb 5 comment Check if a point is within an ellipse @rschwieb yes, it does. Feb 1 comment Find five positive integers whose reciprocals sum to $1$ @JoeZeng We'd probably need assistance from SO staff to get an answer; but I'd be curious if your answer has a disproportionately high share of up votes from people whose network profiles indicate they're primarily programmers not mathematicians. Jan 31 awarded Informed Jan 30 comment Find five positive integers whose reciprocals sum to $1$ More context is needed to judge appropriateness of the difficulty. eg Regular vs honors math, and if it's something that all students are expected to be able to do or a stretch problem. It appears similar in difficulty to weekly challenge/puzzle solving sets that I was regularly given in my honors math class around that grade level; but the typical expectation was that we'd only be able to figure out how to solve 2 or 3 out of 5 of them (and the 'easier' half were generally solvable both via brute force using just pencil and paper and by a more elegant method if you could figure it out). Jan 24 comment How many ways can 1's and 2's be added to equal 17 if order matters? @Dave even if you didn't feel comfortable asserting that the sequence was Fibonacci's and using a formula to compute the 17th term directly, computing the first 17 terms sequentially can be easily done without knowing the sequence is anything special. Jan 11 comment Computing $999,999\cdot 222,222 + 333,333\cdot 333,334$ by hand. @DumbCow more generally (2/3)A * (3/2)B = A * B Dec 17 comment Can't argue with success? Looking for “bad math” that “gets away with it” This is reminding me of an anecdote about a physicist from the early 20th century with a reputation for making arithmetic errors who as a joke intentionally made a huge order of magnitude error (10^10???) in a published paper; and then published a correction the next month noting that the error didn't affect the results of the computation. Unfortunately I'm failing to Google it so I can't see if what he did would be relevant to this question or not. Nov 20 comment Finding the 2,147,483,647th prime number @Artes Is Mathematica consulting a lookup table; or actually calculating the first N primes in order to return Prime[N]? Oct 30 awarded Teacher