But I enjoy solving problems, e.g., http://publicsphere.org/2014/02/07/exercise/ http://publicsphere.org/2014/01/04/fibrations/ http://publicsphere.org/2013/12/23/markets-and-market-games/ http://publicsphere.org/2013/12/14/elementary-equivalence/ http://publicsphere.org/2013/12/12/another-problem/ http://publicsphere.org/2013/12/08/problems/
I have many more in password-protected blogs, notes, etc.
This morning a friend informed me about Oppia https://www.oppia.org/. I took a few minutes to solve their introductory example, Euler Project Problem 1 (Question: What is the sum of all the multiples of 3 or 5 below 1000?). I did this in Mathematica by combining inclusion-exclusion (expressed via indicator functions if you like) with little Gauss's formula for summing the integers from 1 to n.
SumN35[n_] := 3SumN[Floor[n/3]] + 5SumN[Floor[n/5]] - 15*SumN[Floor[n/15]] where SumN[n_] := Binomial[n + 1, 2]
I got SumN35[999] = 233168.
[OT lamentation ahead] Unfortunately, in my experience, employers don't seem to value this activity--at least I tend not to impress them as a confident person who will passionately defend his answers until shown wrong. I don't have the personality, patience and energy for this kind of bravado. (I have an acquaintance who has the requisite unaesthetic attitude, who is not more intelligent that I am and who landed a job at Google.) I tend to have inspirations that come from nowhere that I have to go back and reason about. The act of convincing yourself that a correct answer is really correct can sound like a lack of confidence to some individuals. To me, projecting confidence requires extraneous cognitive load, but I can be confident for an additional charge.]
If you tell me that using flash cards is morally wrong, or if you have a theory of learning that invalidates their use, I won't argue.