The GROWTH() function returns predicted y values based on exponential trend line calculated form known values of x and y. The syntax for the function is GROWTH(known_y's, known_x's, new_x's, const). The arguments "known_y's", "known_x's" and "new_x's" can be an array of numerical values, references to a range of cells or a named range. The "const" is a logical value that determines the existence of b (TRUE or omitted calculates b as part of the result, FALSE sets the value of b to 1). The GROWTH function uses the known values of x and y to create exponential trend line it then uses the equation of the trend line and the "new_x's" values to calculate the unknown y values returning them as an array. The form of the exponential trend line is y=bm^x where b and m are calculated by the function. For example: GROWTH({2,4,8,16},{1,2,3,4}, 6, FALSE) = 64. or GROWTH({2,4,6,8,16},{6,7,8},FALSE)= {64, 128, 256}. As the function that describes the exponential trend is y=2^x. [chart] For the function to return multiple values it must be entered as an array formula e.g.

How to use the GROWTH() function: Type " =GROWTH( " Type a comma. Enter the reference for the "known_x" values "B2:B10 ". Type a comma. Enter the references for the "new_x's" values "C2:C10". Type a comma. Enter the value of the "constant". Type")" then press the "Enter" key. Select the range C11:C14. Press the "F2" key then hold down "Ctrl ", " Shift" and press the "Enter" key.

When no unknown_x's are chosen the GROWTH function will return the expected y values that follow the calculated exponential trend of the known x values. The function can be uses to interpolate unknown y values between known x values e.g. GROWTH({2,4,8,16},{1,2,3,4}, 2.5, FALSE) = 5.656854. or directly find the equation for the exponential trend line. [chart] Note: If any other the number in the "known_x" values are negative or equal to zero the GROWTH function returns a #NUM error value.