https://docs.ruby-lang.org/en/master/doc/syntax/literals_rdoc.html

"There is also a character literal notation to represent single character strings, which syntax is a question mark (?) followed by a single character or escape sequence that corresponds to a single codepoint in the script encoding:"

It is in the Ruby documentation. No, it's not Symbols (:Ruby) but it's quite a mess since originally this was intended as a Number literal but doing ?a to get 97 was confusing and it wasn't intuitive so now it's a String and people can just do ?a.ord for 97.

Sorry if this is real nooby question, but why does ?* == * as a string
I cant find anything about ?* in the Ruby documentation
Edit: also how do I put code into the little boxes like Unihedron has?

Checks the binary 1st digit. 1 is odd.

I cant understood...
Awesome solution!

Strings are mutable in Ruby, when the validation function is executed, it uses the value you previously mutated, giving the wrong result.

string_1 = "Hello"
string_2 = " World"
string_3 = string_1 << string_2
puts string_3 #Hello World
puts string_1 #Hello World

You're mutating first_name in your get_full_name method. Use another way to do string concatenation that doesn't mutate your strings.

No, it's not like you claim. You're probably mutating the input or your initializer is wrong. Why don't you show your code? I can't help you if you don't do that.

AFAIK Ruby tests work. It's probable your code is the culprit, can't tell without seeing it, remember to use Spoiler content flag if you post it.

Yeah it's probably not so good -- I think it was giving me trouble and I just went with the first way I could think of that worked.

Hint: you don't have to use floats ;)

State which language you're having troubles with (I guess it's Ruby). I've tried Ruby and it works, so maybe it's your code that doesn't work. Are you mutating the array or something like that?