Asteroseismology has proved to provide precise values of rotation frequencies of rotating stars with hump and spike features in their periodograms. In the presence of reliable values of stellar radius, prcise values of equatorial rotation velocity of hump and spike stars can be obtained. The periodogram of a hump and spike star typically shows a well pronounced sharp frequency peak (spike) at the high end of a forest of frequency peaks (hump). In this study, we determined the rotation velocity and approximated the strength of star-spots based on their size and decay lifetime of normal A and Am/Fm stars. Using the hump and spike features identified in the frequency spectra of these stars, the rotation frequencies and amplitude were computed. The corresponding equatorial rotation velocity (Vrot) and spot size were estimated. By fitting the autocorrelation function of the light-curves with appropriate models, the starspot decay-time scale was determined. A good agreement between the resulting equatorial rotation velocityvalues and the values of the projected rotational velocity in the literature was observed. We considered a single circular and black spot to estimate its radius needed to reproduce the amplitude of the spike. No evidence for a significant difference in the average rotation amplitude and spot radius was found for Am/Fm and normal stars. We do find significant difference for the average spot decay-time scale for Am/Fm and normal A stars, respectively. In general, spots in normal A and Am/Fm stars are similar in size but they are weaker than previously estimated. The existence of the spikes in the frequency spectra may not be strongly dependent on the appearance of starspots on the stellar surface. In comparison with G, K and M stars, spots in normal A and Am/Fm stars are weak which may point towards a weak magnetic field too.