This function needed to return an int array. One way to do this was to build a new array and add the min and max to it and then return. But here you are doing it in one step without giving the array a variable name. You create a new int[] and initialize it all in one line.

How does this approach handle when the resulting "digit" after multiplying by 2 is greater than 9?

I also don't think this solution solves the Kata as written. This changes the class in order to make push a one line function. Since the original class declaration didn't have an argument for next I feel this misses the point.