



Rules  
1.We divide 80 numbers into 8 extents. Each extent has 10 numbers and is like [110],[1120],...,[7180].  
2.'Sum' in the table above means the sum or total of 20 numbers.  
3.Frequence of extent means the number of occurrence within the extent. For example, if numbers of the result which are under 10 are 1,2 and 5. Then the frequence of extent [110] is 3.  
Examples  


