In all my undergrad and graduate level Physics, I don't think I ever used the value of R. The answer has nothing to do with the numerical value--that you can google. It has to do with knowing how to solve the problem.
Though having a grasp of the numbers can help with scale and the often forgotten "does that make any reasonable sense" check.
Though having a grasp of the numbers can help with scale and the often forgotten "does that make any reasonable sense" check.