+328 The following are all 24 numbers made of digits 1, 2, 3, 4 exactly once:
1234,1243,1324,1342,1423,1432,2134,2143,2314,2341,2413,2431,3124,3142,3214,3241,3412,3421,4123,41324213,4231,4312,4321
What is the average of these 24 numbers? Please express the result in decimal form.
