Jeronimo and Aleks sent me these:

P.S. Actually, I don’t like the first one above because it’s so obviously fake. I mean, they might all be fake, but it’s clear that nobody would ever be given a question of the form, “1/n sin x = ?”. It just doesn’t mean anything. Somebody must have come up with the “six” idea and then worked backwards to get the joke.

The third one also looks fake, in that who would ever be given something so simple as 3,4,5. But who knows….

P.S. Corey Yanofsky sent this:

It always make me smile when I get to hear/see the same joke via multiple acquaitances and how much is the time elapse. Someone has sent me the second one about a month ago. What does this say about my social network? :)

Tian,

I think Aleks sent it to me about a month ago. It just took me awhile to post it.

here is another: 64/16=4

but the answer is arrived at by cancelling out the 6s. Right answer but wrong method.

The first one can be modified to make more "asymptotic" sense:

lim_{n oinfty} 1/n sin x = lim_{n oinfty} six = 6

Empedocles,

It's still not plausible, because why would you have 1/n attached to sin x? I think someone was looking at "sin x" one day and realized that if you get rid of the "n" you have "6".

I've seen the third example (find x …) before. it was supposed to be a GCSE Maths exam question (England and Wales exams for 16 year olds). Given that there are different versions of the exam it is fairly plausible that the easier papers might include that among the easier questions. This is confirmed by looking at mock papers produced by the BBC as revision aids (e.g., the non-calculator foundation paper):

http://www.bbc.co.uk/schools/gcsebitesize/maths/m…

Thom

Building up 64/16 = 4, we also have 95/19 = 5 — one might try and think about generalizations of this "rule" …