> Hint: if the last character is not alphanumeric, put a # (a blank URL fragment) to work around HN's autodetection of punctuation

I usually use URL encoding (aka percent encoding) [0] in this case but that’s a pretty neat trick and certainly more convenient than for example pasting the URL into https://meyerweb.com/eric/tools/dencoder/ and pressing the encode button and copying the encoded URL.

[0]: https://en.wikipedia.org/wiki/Percent-encoding

So, fun fact about percent-encoding: the space character can be percent encoded as %20 or +, and a literal plus must always be percent encoded as %2b. When you put plusses in Google Search those are actually pre-percent encoded spaces, which is why it treats them as spaces. Of course, if you chuck it into a percent encoding script again it treats them as literal spaces since presumably the input isn't already percent encoded (just as it'd encode the % in other encoded characters).

At least that's if I recall correctly and it wouldn't surprise me if other servers do handle things in zany ways.