New fissile isotopes antineutrino spectra ($^{235}$U, $^{238}$U, $^{239}$Pu and $^{241}$Pu) calculation is presented. On base of summation method the toy model was developed. It was shown that total antineutrino number is conserved in framework of given database on individual fragments yields. The analysis of antineutrino spectrum shape says that any presented antineutrino spectrum should satisfy to the total antineutrino number conservation.