Returns the greatest common divisor of two or more integers. The greatest common divisor is the largest integer that divides both number1 and number2 without a remainder.
If this function is not available, and returns the #NAME? error, install and load the Analysis ToolPak addin.
How?
 On the Tools menu, click AddIns.
 In the AddIns available list, select the Analysis ToolPak box, and then click OK.
 If necessary, follow the instructions in the setup program.
Syntax
GCD(number1,number2, ...)
Number1, number2, ... are 1 to 29 values. If any value is not an integer, it is truncated.
Remarks
 If any argument is nonnumeric, GCD returns the #VALUE! error value.
 If any argument is less than zero, GCD returns the #NUM! error value.
 One divides any value evenly.
 A prime number has only itself and one as even divisors.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example
 Create a blank workbook or worksheet.
 Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help
 Press CTRL+C.
 In the worksheet, select cell A1, and press CTRL+V.
 To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.

A 
B 
Formula 
Description (Result) 
=GCD(5, 2) 
Greatest common divisor of 5 and 2 (1) 
=GCD(24, 36) 
Greatest common divisor of 24 and 36 (12) 
=GCD(7, 1) 
Greatest common divisor of 7 and 1 (1) 
=GCD(5, 0) 
Greatest common divisor of 5 and 0 (5) 
