AVERAGE(DataArray): Computes the average of the cells in the DataArray (range of cells); non-numeric cells are ignored.
AVERAGEA(DataArray): Works exactly like the AVERAGE function but non-numeric cells are taken as zeros; Logical "TRUE" evaluates as 1.
COUNTIF(DataArray, Criterion): Counts the cells, in the data array (range of cells) that meet the criterion [e.g., suppose that cells A1:A5 contain the words "maybe","yes","yes","maybe","no", respectively, & cell B1 contains the formula COUNTIF(A1:A5,"yes") ; then the value of B1 is 2]. 
CORREL(ArrayX,ArrayY) Provides the correlation coefficient between an array of X values and an array of Y values
FREQUENCY(DataArray, BinsArray): provides an array of frequencies from an array of values. 
IF(LogicalTest, Value1, Value2): Depending on the logical test, the cell takes on Value1 (if test result is true), Value2 (if false) [e.g., suppose that cell A1 contains the word "maybe" & cell B1 contains the formula IF(A1="yes", 3, 5) ; then the value of B1 is 5].
INT(value): Computes value (may be a formula) & rounds to the largest whole number less than value. (e.g., INT(5.3) is 5; INT(-5.3) is -6)
MAX(set of numbers/ranges):  Assumes the largest number in the set. (e.g., MAX(A1:G5, X1, Y5:Z14))
MIN(set of numbers/ranges):  Assumes the smallest number in the set. (e.g., MIN(A1:G5, X1:Z14))
NORMSDIST(Z): Provides the value of the cumulative standard normal, N(0,1),  for the given value Z 
NORMDIST(X, Mean, StandardDeviation, Cumulative): Provides the value of the normal, N(mean, std dev), for the given value X. If you want the cumulative make the 4th parameter "true"; for the regular normal, make it "false";
NORMINV(Probability, Mean, StandardDeviation): This is the inverse of NORMDIST; it provides the X-value of the normal, N(mean, std dev), for the given probability. For ex, the formula NORMINV(0.8413,10,2) will produce the value 11.999 (converts to Z=1). In order to generate normally distributed random numbers, use NORMINV(RAND(),10,2).
NORMSINV(Probability): This is the inverse of NORMSDIST; it provides the Z-value of the cumulative standard normal, N(0,1), for the given probability. For ex, the formula NORMSINV(0.8413) will produce the value Z=1. In order to generate N(0,1)-distributed random numbers, use NORMSINV(RAND()).
RAND(): Provides a random number between 0 and 1 to 5 decimal places (e.g., 0.74922)
RANDBETWEEN(Value1, Value2): Provides an integer random number between Value1 and Value2. This function is part of the "Add-In" Analysis Package that must be "installed" (Navigate: Tools  ==>Add-ins...==>Analysis ToolPak).
Random Number Generation: (An Excel Add-in) (Navigate: Tools menu --> Data Analysis --> Random Number Generation ) Allows the generation of random numbers according to several standard distributions such as the normal, Poisson, binomial, etc.
Regression (An Excel Add-in) (Navigate: Tools menu --> Data Analysis --> Regression)
SQRT(Value): gives the square root of Value.

Use class notes & the Excel "Help" facility for additional instructions on how to use these functions