Fun with ASINs

I was remarking today that you could get a rough estimate of the total number of distinct items ever listed in Amazon's catalog by taking a recently assigned ASIN, subtracting B000000000 from it, and converting the result from base 36 to base 10.

R. and I decided to play this game. We think Amazon has probably passed 100 billion ASINs at this point.

I don't ever expect to see an ASIN starting with the letter C (and if I see that anytime soon, I'm gonna start making phone calls and asking WTF they are doing over there anyway). But that 100 billion is a big, big number nonetheless. It just doesn't seem that big, in base 36.

ETA:

Here is an example. Wilco pre-announced _Schmilco_, with ASIN B01I2DUUQK. I used this converter:

http://www.translatorscafe.com/cafe/EN/units-converter/numbers/39-13/base-36-base-10/

And assuming I didn't type anything in wrong, got this number: 117690453020