Original sentence: If we want to measure the entropy in terms of bits, then we must choose k = 1/ln(2) so that.In case of thermodynamics, one often deals with a system of which the volume, internal energy and number of molecules in the system is known.The choice for the constant k is the Boltzmann constant kB = Boltzmann's constant = 1.38066×10−23 J K−1.The exact states the system can be in are the many particle quantum states the molecules can be in
Edited sentence: If we want to measure the entropy in terms of bits, then we must choose k = 1/ln(2).In case of thermodynamics, one often deals with a closed system of which the volume, internal energy and number of molecules in the system is known.The number of molecules in the system is often huge and as a consequence, there are a huge number  of quantum states the system can be in.The probability distribution over the set of quantum states is assumed to be uniform, so we have.The standard choice for the constant k in thermodynamics is the Boltzmann constant kB = Boltzmann's constant = 1.38066×10−23 J K−1.This then leads to the formula: