All these operators create a new sequence that will flow a single message containing the minimum, maximum, averaged, sum, or count value ever entered in the operator from the source sequence. The new sequence will flow out its message only when the source sequence is complete.

Here is an example:

var s16 = new Subject<double>(); 
var min = s16.Min(); //register for finding the min 
var max = s16.Max(); //register for finding the max 
var avg = s16.Average(); //register for finding the average 
var sum = s16.Sum(); //register for finding the count 
var count = s16.Count(); //register for finding the sum 
 
min.Subscribe(x => Console.WriteLine("min: {0}", x)); 
max.Subscribe(x => Console.WriteLine("max: {0}", x)); 
avg.Subscribe(x => Console.WriteLine("avg: {0}", x)); 
sum.Subscribe(x => Console.WriteLine("sum: {0}", x)); 
count.Subscribe(x => Console.WriteLine("count: {0}", x)); 
 
//some value 
var r = new Random(DateTime.Now.GetHashCode()); 
for (int i = 0; i < 10; i++) 
    s16.OnNext(r.NextDouble() * 100d); 
 
//now aggregation operators will flow their message 
s16.OnCompleted();