Haha, Billy has got the bug. I am reminded of an amusing cycling rule list someone posted a couple of years back. They had a rule on how many bikes you should own. They honed it down to two equations
Nbd = n+1
Where:
Nbd = the desired number of bikes owned
n = current number of bikes owned
However this equation is limited by this overriding equation
Nbo = d-1
Where:
Nbo = Optimum number of bikes
d = number of bikes which would lead to divorce