Floating through the nodegel today, I started reading through Johnath's writeup on combinatorial explosion when I came across this phrase in his calculations. Being the math nerd that I am, I just found this too cool to pass up, so I worked it out for myself:

1 nanocentury

=

10^{-9} centuries × 100 years/century × 365.25 days/year × 24 hours/day × 60 minutes/hour × 60 seconds/minute

=

3.15576 seconds

Percent error from *π* seconds: |3.15576 - *π*|/*π* = **0.45%**

Naturally, I find this to be pretty damn cool. If anything, it makes a great mnemonic, but I have to wonder if there are any other strange wonderful coincidences like this in our unit system. I bet *e* feels jealous.

An example of this in use (at the request of m_turner, who also informs me that this conversion factor can be found in Programming Pearls) would go something like this: Suppose you have a program that needs to execute 10^{8} instructions, and each instruction takes 1/3 of a second. How long would the program take to execute? Of course, you could run through all the conversion factors from seconds to years, but who wants to do that?

10^{8} instructions × 1/3 seconds/instruction × 1/*π* nanocenturies/second × 10^{-9} centuries/nanocentury × 100 years/century

=

1.061 years

So nice.