( duplicate comment )

That's what you get, sometimes, with translated kata. There are technical reasons for not changing the original description.

If it's very unclear what the ( type of the ) expected return value should be, please raise another issue.

Closing.

temporary issue of CW's servers, not an issue of the kata. Closing.

Help us help you. Tell us in which language you have this problem.

add a "s" behind the "play"

You should provide more details on why adding String in loop is a bad practice (performance issue) and a solution (StringBuilder). I don't remember this kata but a Regex compiled in a loop plus a Scanner are overkill and even worse than a String adding. A better way is to use Pattern/Matcher and parse... function from Double and Integer.

In any case this code is not a 'Best Practices', but a quick-and-dirty simple solution.

It's run a predicate against number that first converted to string. Predicate is an interface with single method boolean test(T object) (T is a String in this case).
With Stream.of(...) we creates a stream of predicates. And with anyMatch(...) we test each predicate if it's returns true for incoming number.

trim the string that you are returning.

You're not returning the correct result.