I previously posted when I found that the largest number you could use in Google Calculator is 2^1024 [1]. This is the smallest number with exactly n divisors [2], where n is the answer to life the universe and everything. The result of a search for the most precise form of that number that Google would accept is 1.79769313486231580e+308 at Everything2 [3]. At the time, Google Calculator didn't like working with a very precise decimal representation, but now it is just fine with using 307 out of the 308 digits! [4] It will not allow you to work with the binary representation of this number as it is too long (1,022 digits).

At this point I wondered why there is such a limitation for the scientific notation when there is a virtually unbounded decimal representation. I believe the answer to this question is that 1.79769313486231580e+308 is the largest number you can fit in a C++ double, and that python supports arbitrarily long numbers in its long data type. Certain routines would have to be rewritten using python's long data type in order to support a more precise representation in scientific notation. This is just a WAG :) [6]

[1] blogoscoped.com/forum/11949.ht ...
[2] research.att.com/~njas/sequenc ...
[3] google.com/search?client=safar ...
[4] google.com/search?hl=en&lr ...
[5] python.org/doc/2.2.3/ref/types ...
[6] acronymfinder.com/af-query.asp ...