A. Intalnire 

Impreuna cu Petru urca in metrou 3 perechi sot – sotie care prind trenul chiar inainte sa plece din statie. In metrou, incep prezentarile. Cand se fac prezentarile, fiecare persoana strange mana persoanelor pe care nu le cunoaste. Pentru ca la plecare trenul de metrou nu este deloc silentios, Petru reuseste sa auda un singur nume: Liviu. Apoi il aude pe Liviu exclamand: ”Ciudat, fiecare dintre voi a strans mana unui numar diferit de persoane”. Petru afla astfel cate mani a strans sotia lui Liviu. Cate?

Sursa: adaptare (Ruxandra F. Olimid, dupa o problema de Martin Gardner)

A. Meeting people

Together with Petru get into the train 3 couples that catch the train just before leaving the station. In the train, they introduce to each other. When presentations are made, each person shakes hands with persons he/she does not know. Because the underground train is quite noisy, Petru manages to hear a single name: Liviu. Then he hears Liviu’s words: "Strange, each of you has shaked hands with a different number of persons." Peter knows how many hands did Liviu's wife shake hands with. How many?

Source: adaptation (Ruxandra F. Olimid, after a problem of Martin Gardner)