A peculiarity of M-theory when combined with gauge/gravity duality is that the free energy of the gauge theory on M2 and M5-branes follow a power law: N^{3/2} for M2, and N^3 for M5 when the number of branes N becomes large. This property has been considered mysterious for many years, but thanks to recent progress we now have a sound understanding and also semi-microscopic derivations of the scaling behaviors quoted above. Here we present field theory computations at large N in particular, and illustrate how the results come out in agreement with the prediction of AdS/CFT including coefficients.