String isn't mutable, every time you change string, you actually create a new string in string pool. That is why, it's better to save index of maximal string in array of strings. But your solution is still clever and understandable.

It wasn't forbidden by task, but it can be problem in real life. I agree with you.

If score is "10:9" this function will break.

Best solution! I did it simular way.

Clever but redundant

Why didn't you write return n * 2 - address + 1;?

I was afraid that there would be phrases like "TREE FIDDY" or "THREE FIFTY", and wrote unnecessary command s.toLowerCase().

You can take 2 out of brackets.

Using algebraic progression is cool!

Clever solution, but if n is too big, it can cause stack overflow.

This guy is pranking.

Why do you actually need else if? If Compiler went to second raw, it automaticly means that n > 5 is false.

Why do you need ternary oprearor?

Because you try to assig int to BigInteger. i variable is int, and Math.Pow(2, i) also returns int.