Molar gas constant ($R=N_A{k}_B$)

The molar gas constant is the product of the Avogadro constant and the Boltzmann constant. It converts the particle-number form of the ideal gas law, $pV=N{k}_{B}T$, into the amount-of-substance form $pV=nRT$, using $N=n{N}_A$ with $n$ measured in moles.