Question about XKCD for 1/11/2010

[gar3555]

I read todays XKCD, and was trying to figure out if the formula actually worked. I am having difficulty proving it out. I was wondering if anyone else could prove it.

xkcd

here is what I found so far:

planck energy
0.5433 MWh
1.956 × 109 J
1.22 × 1019 GeV

Pressure at earths inner core
330 to 360 GPa

Prius combined mileage
46

English Channel
21 mi.

most of these are from wiki, the prius mileage is from fueleconomy.gov

 

[PottedMeat]

the units work out, but i get 3.14387

i used 360GPa
edit: all hail the ti-89 for working out all that annoying unit shit.