Weird averages problem

[buffalo]

Hi,

Here's the problem:

Suppose I have a column with numbers that I keep adding new numbers to.
Now I know the running count and the running total somewhere

Next when I input the new value, I need to know the avg of all values inthe column EXCEPT this new one, let us call it the "Previous AVG". Because the running count and the running total will immediately change when I add this new value, I cannot the calculate the "Previous average"...

Could anyone suggest a method I can do the above using the running count and running total for every new entry ?

VBA or worksheet, anyway is fine.

thanks

 

[Legacy 21301]

=(SUM(A:A)-LOOKUP(9.99999999999999E+307,A:A))/(COUNTA(A:A)-1)

 

[buffalo]

Thanks a lot.