It is becuase of the size of the number - excel can only deal with (i think) 15 significant figures and anything else is rounded.


For exmaple if you put 377540323190869743517.9993055556+0 in an other cell it will show as 3.7754e+20, then increase decimals to the max and you will see the cell is actually showing 3.775403231908690000000e+20..


Drop off the zeros and filter for 377540323190869 and you will get 16, which is how many the count is counting.


Now to get around that.......