Biswajit Karmakar, Krzysztof Grzanka, Janusz Gluza, Bartosz Dziewit and Ievgen Dubovyk visited CERN from 29.05 to 18.06 as a part of the UŚ-CERN FCC scientific cooperation. In parallel we took part in the two-week Precision calculations for future e+e- colliders: targets and tools workshop, where Janusz Gluza gave a talk on Feynman parametrization and numerical integration.