Numerals represent a specified semantic field, where deep archaisms can appear besides recent loans in various language groups. The comparative method allows us to stratify different layers in lexicon: 1. Substrata; 2. Inherited lexicon; 3. Adstrata. 4. Superstrata. Socio-linguistics mentions situations, when forms of the same meaning, but of various origins, are used in parallel, one alongside another. In the present contribution we study the numerals in Mongolic and Tungusic languages, including analysis of their etymologies, identification of interferences and description of their use in code-switching. In the past this phenomenon could have played a role in the process of adaptation of foreign forms, including numerals, in the same way as in the present. The carefully analyzed stratigraphy of lexicon allows us to identify which of its parts are inherited, which borrowed, from which source and in which period. These results can be used for the determination of original homeland, trajectories of migrations and positions of neighbors.