> One striking characteristic of Grothendieck's mode of thinking is that it seemed to rely so little on examples. This can be seen in the legend of the so-called "Grothendieck prime". In a mathematical conversation, someone suggested to Grothendieck that they should consider a particular prime number. "You mean an actual number?" Grothendieck asked. The other person replied, yes, an actual prime number. Grothendieck suggested, "All right, take 57."

cbolton 2 hours ago | parent [-]

I had to follow your link to get it: I hadn't realized that 57 is not prime. At least I'm in good company.

	▲	karmakurtisaani 39 minutes ago \| parent \| next [-]
		It looks like a prime, but can be caught with the second-simplest test: sum of the digits is 12, which is divisible by 3. Hence it's divisible by 3. (The simplest test being of course if the number is even and bigger than 2) Edit: now that I think about it, probably should not have tried to impose ordering to the simplicity of tests. There's of course the divisibility by 5 test, which is even simpler.
	▲	Npovview an hour ago \| parent \| prev [-]
		Take 111 as an example.