How can we use group functions on IObservable while observing is not finished or on hot, long running observable

How can we use group functions on IObservable while observing is not
finished or on hot, long running observable

I have the following Observable
IObservable<int> observable = Observable.Range(0, 10);
I have the following subscriptions
observable.Subscribe(v => Console.WriteLine("Received value: " + v);
observable.Sum().Subscribe(s => Console.WriteLine("Sum so far: " + s);
My desired output is following
Received value: 0
Sum so far: 0
Received value: 1
Sum so far: 1
Received value: 2
Sum so far: 3
...
...

But what I am actually getting is the Sum after receiving the final value
of the series.
My actual goal is to fit this into the puzzle where I have a Hot,
continuously running observable giving me decimal values and I have to
subscribe() to the current average and sum values.
Any help in this will be appreciated.