A simple recursive macro: GCD
p>In mathematics, the greatest common divisor (abbreviated GCD), or highest common factor (HCF) of two integers which are not both zero is the largest integer that divides both numbers.
The GCD of a and b is often written as gcd(a,b) or simply (a,b). For example, gcd(12,18) = 6, gcd(-4,14) = 2 and gcd(5,0) = 5. Two numbers are called coprime or relatively prime if their greatest common divisor equals 1. For example, 9 and 28 are relatively prime.
The greatest common divisor is useful for writing fractions in lowest terms.
The algorithm for determining the GCD of two numbers is known as a recursive algorithm - and the OpenOffice Basic code is listed below..
Function gcd(a As Integer, b As Integer) As Integer
If b = 0 Then
gcd = a
Else
gcd = gcd(b,a)
End If
End Function