I should have used a little more time on this one. I used a Test Fixture example, as an example, I'll expand the description a bit. The intend is to make it easy and return '' + num is a legit way.

I agree the kata is good to go as it stands. However, I think the author should review the solutions to ensure that the solutions most of us are coming up with, just to make sure they're within the author's intent.

I agree. I think examples in the description are always a good idea. Though I'd format the examples like:

Examples:
numberToString(123); // returns '123';

I think this kata's good to go. The lack of examples isn't a huge deal because the description clear.