Apparently the function has to be named 'square', which you only realize with the error message after attempting it. Very very poorly described Kata, in my opinion.

Nice clean code. Good Job!

Simple and efficient !

Nice!

Please use spoiler flag next time, your post was visible in the homepage.

Well this is a good method because i can also change a number to binary with base 2. Normal String(num) method cannot do that !

try it, i think it just wouldnt return the val?

I was trying for a while, then I saw your solution and I was like '-'

simple ♥

But it's slower

I think the testing unit is checking what your function has returned matches the correct answer it has and it doesn't check what you have printed on console.
e.g. checkAnswerWithCorrectAnswer( numberToString(123), '123')

did you figure out why?

Wow nice solution!

because it can change the radix.