Useful factoid

[Robert J. Hansen]

Accurate to 6%, there are 2**25 seconds in a year.  Worth remembering:
it makes certain kinds of computations much easier.  (It follows there
would be about 2**35 seconds in a thousand years, or 2**45 seconds in a
million.)

E.g., let's say you want to brute-force an 64-bit key on a CPU that can
do a million (2**20) attempts per second.  This requires, on average,
2**63 attempts.  2**63 / 2**20 = 2**43 seconds: 2**43 / 2**45 = 2**-2 =
a quarter of a million years.

I don't know why it took me so long to notice that: seems like the sort
of thing I should've noticed a decade ago.  It makes certain kinds of
computations so much easier.

Anyway, figured I'd throw it out on the off chance there were others who
hadn't noticed it.