C={2,7,9,11}
submultimile:Ф,{2,7},{2,9},{2,11},{7,9},{7,11},{2,7,9},{2,7,11},{2,9,11},{7,9,11},{2,7,9,11} etc.
Nr de submultimi ale unei multimi se calculeaza ca 2ⁿ,unde n este numarul de elemente din multime.
Deci nr de submutimi a multimii 2⁴=16 submultimi
