We don't have the digits of pi for the second part. We only have 22,459,157,718,361 digits of pi which is only ~45 bits not enough to create the image with bits left over for moving it around in pi.
That answers the question of how many bits of pi we know. If you want to be able to take an arbitrary n-bit string and find its position in a set of n-bit strings, you need to have something like 2^n strings in your set.
So to find the number of bits you can support for an algorithm like this, taking the log of the number of digits of pi we know gives you a rough estimate.
The person I was responding to had a two-ish step problem 1) find a number with a binary representation that looks like Mickey 2) find an index for that number in pi that looks like the copyright symbol. Both are conceivably possible because pi is infinite and it's decimal places contain all numbers somewhere but we only know so many actual digits. Since we're dealing with the index of the number from step 1 though the number of bits we have to find the copyright symbol in is only log_2(22,459,157,718,361) ~= 45 because it's the index we're after.
