Hi! This is very clever. But I fail to imagine my self ever thinking of this. Can you please tell me how this style/techniqeu is called so I could learn it and practice it more?

Where did you check the cube value of each digit?

Ignore the comments, I didnt understood the exercise then.

I keep getting this error -> "undefined method `name' for nil:NilClass
Simplified backtrace: block (3 levels) in <top (required)> -> block in each -> block (2 levels) in fetch_rows -> each -> block in fetch_rows -> query -> block (2 levels) in _execute -> log_connection_yield -> block in _execute -> block in synchronize -> hold -> synchronize -> _execute -> execute -> execute -> fetch_rows -> each -> block (2 levels) in <top (required)>"

I dont see how this could fail. If you get 50bill you only need 25, if you get 50, you need 75 (50+25|| 25 + 25+25), doesnt matter, if there would be more bills, then it wouldnt work. I think. Its just so simple you dont want to believe it. I think this is pretty clever.

Very nice! At first I thought that cant be right, didnt read it properly, but its was just so simple I wanted to believe it was wrong :D

I understand how you are feeling, I thought the same thing, that if n is square number we should return -1, apparently my whole algorithm means nothing now (hiting my head against a wall)
Edit: I over exagirated, turns out deleting one line fixed it, for now. :)

I find this very difficult to understand

When I was doing GroupBy module it was returning the module not the number moduled. Was it because I was returning the key not the item?

Nice! Thank you! Before this I was just guessing what could crash my code.

Why cant I pass the random tests? Why cant I see the random tests? At least then I would know where is the problem. Overall I think this was a good and useful problem, just dont understand whats wrong with my code.