The number of subjects will depend on what the elements of the set are. The number of subsets is 2a.
A set with n elements has 2n subsets. The number of proper subsets is one less, since 2n includes the set itself.
That means, figure out how many different subsets a set has. In general, if a set has n elements, it has 2n different subsets.
To get the number of subsets of size less than 2:Total number of subsets of a set of size N is 2NTotal number of subsets of size 1 is 100Total number of subsets of size 0 is 1Total number of subsets of size 2 is 100*99/2 = 4950Sum up: 100 + 1 + 4950 = 5051Subtract this from total subsets: 2100 - 5051 (Answer)
A set with 9 elements has 2^9 = 512 subsets.
If the universal set contains N elements then it has 2N subsets.
There are 2100 = 1.268*1030 or 1,268 octllion subsets with an odd number of elements.
If you have a set of 6 elements, you can make a total of 26 different subsets - including the empty set and the set itself.