A={1,2,3,...,50}
B⊂A
{1,2,3,…,46} ⊂ B ⊂ {1,2,3,....,50}
Reunim {1,2,3,….46} cu fiecare submultime a multimii {47, 48, 49, 50}.
Sunt 4 elemente => multimea {47, 48, 49, 50} are 2^4=16 submultimi.
=> numarul submultimilor B ale lui A = numarul submultimilor multimii {47, 48, 49, 50} =16
R: 16 submultimi