The problem of calculating the cost of enriched products in cascades with several external feed and selection ows is considered, with the schemes of the latter being not reduced to a set of cascades with one feed. The calculation is based on the accepted condition that the total power of cascade separation was completely distributed between the isotopic values of the external selection ows. It is shown that for such cascades the calculation methods successfully used for single-fed cascades do not make it possible to ful l this condition and correctly determine the cost of commercial products. A form of the potential is proposed that makes it possible to meet this requirement and calculate the cost of all enriched products.