FT_GCD()
 Calculate greatest common divisor of two numbers
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 Syntax

      FT_GCD( <nNumber1>, <nNumber2> ) -> nGCD

 Arguments

     <nNumber1> is the first number to find the GCD of.

     <nNumber2> is the second number to find the GCD of.

 Returns

     The greatest common divisor of the 2 numbers, or 0 if either is 0.

 Description

   This function calculates the greatest common divisor between 2 numbers,
   i.e., the largest number that will divide into both numbers evenly.  It
   will return zero (0) if either number is zero.

 Examples

     ? FT_GCD(10,15)                  // Result: 5
     ? FT_GCD(108,54)                 // Result: 54
     ? FT_GCD(102,54)                 // Result: 6
     ? FT_GCD(111,17)                 // Result: 1

 Source: GCD.PRG

 Author: David Husnian