We present two independent estimates of the number of nucleon-nucleon collisions (Ncoll) and the number of participant nucleons (Npart) in AA and pA interactions at the LHC energies, obtained using Monte Carlo calculations: the Modified Glauber model (MGM) and more detailed "non-Glauber Model", based on the color dipoles approach. Contrary to generally used standard Glauber model, the MGM takes into account in an effective way the energy-momentum conservation in soft particles production. Thus it provides with only one parameter the quantitative description of scaling of the charged particle yields with Npart, describing observed in experiment in a wide energy region from SPS to LHC. The second model provides parton-string description of pp, pA and AA interaction considering the energy conservation in nucleon-nucleon collisions and string interaction (string fusion). These estimates are confirmed by calculations using the MC event generators (AMPT and HIJING). The results are pointing at the effect of notice