Question

what is the approximate boltzmann formula

Answer 1

In statistical thermodynamics, Boltzmann's equation is a probability equation relating the entropy S of an ideal gas to the quantity W, which is the number of microstates corresponding to a given macrostate:

Answer 2

S=KlogW
where k is Boltzmann's constant equal to 1.38062 x 10−23 joule/kelvin and W is the number of microstates consistent with the given macrostate.