Do you mean the Golden Mean?
Consider a line split into two segments a and b, so the line length is a+b. If the longer segment is a and b/a=a/(a+b). The ratio of a to b is the Golden Ratio or Golden Mean.
b(a+b)=a^2, a^2-ab-b^2=0, a^2-ab+b*2/4-b^2=b^2/4, (a-b/2)^2=5b^2/4, a-b/2=±b√5/2, a=b/2±b√5/2.
So 2a/b=1±√5=3.236 or -1.236, making a/b=1.61803 approx (we can reject the negative solution because a and b are both positive). So the Golden Ratio or Golden Mean is 1.61803. The reciprocal of this is 0.61803. Therefore we have that the difference of the Golden Mean and its reciprocal is exactly 1, that is, G-1/G=1.