b=6.5179 - this is the approx. value of b
6.5179 / 7==0.931128571428 this is the first term of an infinite GS
7 ==0.931128571428 / [1 - r], solve for r
r ==0.866981632653061 - this is the common ratio of the infinite GS
Sum=0.931128571428 / [1 - 0.866981632653061] ==7
