The GROWTH function calculates predicted exponential growth by using existing data. GROWTH returns the yvalues for a series of new xvalues that you specify by using existing xvalues and yvalues.
Syntax
=GROWTH(known_y’s,[known_x’s],[new_x’s],[const])
Arguments
Argument  Description  

known_y’s  The set of yvalues you already know in the relationship y = b*m^x


[known_x’s]  Optional. An optional set of xvalues that you may already know in the relationship y = b*m^x


[new_x’s]  Optional. Are new xvalues for which you want GROWTH to return corresponding yvalues


[const]  Optional. A logical value specifying whether to force the constant b to equal 1

Note: If more than one new yvalue is to be calculated by the GROWTH function, the new values will be returned as an array. Therefore, the function must be entered as an array formula.
 Formulas that return arrays must be entered as array formulas after selecting the correct number of cells.
 When entering an array constant for an argument such as known_x’s, use commas to separate values in the same row and semicolons to separate rows.
Examples
A  B  C  D  E  

1  Month (Xs)  Sales (Ys)  Corresponding Units  nowrap  
2  2  330  338.39  
3  3  480  472.20  
4  4  650  658.92  
5  5  1,000  919.47  
6  6  1,200  1,283.06  Array formula used in C2:C7  
7  7  1,800  1,790.41  {=GROWTH(B2:B7,A2:A7)}  
8  
9  New Xs  New Ys  Array formula used in B10:B11  
10  8  2,498.37  {=GROWTH(B2:B7,A2:A7,A10:A11)}  
11  9  3,486.28 
Note: The curly brackets, { and }, seen in the formula entered in D7 and D10 are not entered by the user. Excel applies these to show the formula has been input as an array formula.
Common Function Error(s)
Problem  What went wrong 

#VALUE!  Occurs if any of the values in the supplied known_y’s, [known_x’s] or [new_x’s] arrays are nonnumeric 
#NUM!  Occurs if any of the values in the known_y’s array are less than or equal to 0 
#REF!  Occurs if the [known_x’s] array has a different length to the known_y’s array 
For a single range of xvalues, the equation for an exponential curve is: where,
 x is the independent variable
 y is the dependent variable
 m is a constant base for the x value
 b is a constant which is the value of y when x = 0
If there are multiple ranges of xvalues, the exponential curve equation is: