The set S={1,2,3,...,11} has 11 elements.
We need to count subsets B with n(B)≥2 and even product.
A product is even iff at least one element is even.
Equivalently, count complements: a product is odd iff all elements are odd.
The odd numbers in S are {1,3,5,7,9,11} (6 elements).
Subsets of odd numbers: 26=64.
Among these, those with n(B)≥2 are all except empty set (1) and singletons (6): 64−7=57.
Total subsets with n(B)≥2: 211−1−11=2036.
Subsets with even product and n(B)≥2: 2036−57=1979.