Yes, exactly, .666...7 means a number that has 6 at each decimal position and 7 for index k, where k is greater than any natural number. This exactly is .666... (just as parent commenter explained).
Off-point. Lambdas are different, in the sense that with such functions you 1) need to think about the closure of the function 2) might need to reconsider what part of memory will be executable (you certainly don't want an executable heap). The change here is in the other direction - you remove a feature that is easily swapped with a builtin, which is implemented in terms of other already existing language features.
That is wrong, because quadratic means that the variable is in the base, while exponential will tell you, that the variable is in the exponent (just as the name tells).
It can be done with any byte. In CRC, you encode your input to a polynomial somehow, take an agreed-upon polynomial (dependent on the type of CRC, not the input data) - call it P. Compute the remainder of the input when divided by P, encode it, and that's CRC. So to get any desired CRC, you just need to solve a linear equation (in quite a lot variables, but it doesn't really matter). All in all, it's really easy.
Quick and honest question: are you the author? You respond to lots of comments in the name of author, that's a rather surprising level of care about a niche piece of software.
There's another problem, if the author tells us that this is crc, while it's a MAC (not particularly strong tbh), it shows that we, as developers and users, cannot trust that cryptographic decisions of the author are of any consideration. For reference, crc is not a signature, its full name is "cyclic redundancy check", which is a really simple mathematical operation, that computes a specific remainder that comes from polynomial long division (of polynomials decided from the message). It is not any kind of cryptographic signature and given a string, it's crc and target crc, we can find another string that differs in one byte only, that has the target crc, all of this in time faster than computing whole original crc.
If you can voice out your opinions only if they agree with the supported policy, then it's hard to tell that it's legitimate Chinese opinion. You are standing before a giant selection bias.
That's just foolish - you don't need passwords of any kind. In fact you don't need accounts. You can just store cookies, accessible from this browser only, which tells you what have you solved.