I was feeling pleased that I found and multiplied the digits without converting/parsing strings, but this method of doing it is brilliant!

Nice way to traverse the digits!

Very true ! thanks

Writting down the detailed steps on a paper helped me to clarify the algo ;)

So basically solution can be reduced to 2*(x1 * 2^0 + x2 * 2^1 + x3 * 2^2 ... xn * 2^n-1) + 1 or something similar, I see it now when I write it on paper, but why?
Is that generally known or you came up with this because of this kata?

Thanks for your answer.
It doesn't help me to find what tests are done in SinglePairNoNestingTests but it helps :)

I'm pretty sure there are no tests that define the opening/closing characters more than once in separate pairs.

So by definition yes it should work, but you are trying to achieve more than the kata requires you to.

For the record, I wouldn't be surprised if the reference implementation I wrote failed on this test. :)

I'm trying to understand what hides the test SinglePairNoNestingTests :) and I'm facing a question :

Should this be ok or not ?
Kata.IsBalanced(")(", "())(")

Funny code :)