The Excel SMALL function returns the k'th smallest value from an array or a range of cells containing numerical values.
The format of the function is :
where the function arguments are:
array    An array of numeric values that you want to return the k'th smallest of 
k    The index  i.e. the function returns the k'th smallest value from the supplied array 
The array argument can be supplied to the function either directly, or as a reference to a range of cells containing numeric values. If values in the supplied range of cells are text values, these values are ignored.
The following example shows the Excel Small function, being used to retrieve the 1st, 2nd, 3rd, 4th and 5th smallest values from the set of values in cells A1  A5.
The format of the functions are shown in the spreadsheet on the left and the resulting values are shown in the spreadsheet on the right.
Formulas:

Results:

Note that, any calls to the Small function, in which the index, k is set to 1, gives the same result as the Min function.
In the example above, the functions in cells B1 and B5 could be replaced by the Min function and the Max function, respectively.
Further information and examples of the Excel Small function are provided on the Microsoft Office website.
If you get an error from the Excel Small Function, this is likely to be the #NUM! error:
#NUM!    Occurs if the supplied k is less than 1 or greater than the number of values in the supplied array. 
Also, the following problem is encountered by some users:
The Small function returns the wrong value, or returns the #NUM! error, even though you believe your value of k is between 1 and the number of values in the supplied array.
Text values, including text representations of numbers within the supplied array, are ignored by the Small function. Therefore, this problem may arise if the values in the supplied array are text representations of numbers, instead of actual values (read more about Excel data types on the Excel Formatting page)
This problem can be solved by converting all array values into numeric values. To do this: