Set Theory :
U = {1,2,3,4,5,6,7,8,9,10,11,12}, S = {2,4,7,9,11}
and T = {4,11}
Find : n(U), n(S) and n(T)
I just want to know what they mean by n(U), n(S) and n(T)

Question

Set Theory :
U = {1,2,3,4,5,6,7,8,9,10,11,12}, S = {2,4,7,9,11}
and T = {4,11}
Find : n(U), n(S) and n(T)
I just want to know what they mean by n(U), n(S) and n(T)

anonymous · Answer

For a set $S$, the notation $n(S)$ is sometimes used to denote the cardinality of $S$, which is basically the number of members of the set.

vecters · Answer

So when they tell me to find n(U) for example, they're asking the number of members of U, right?

xapproachesinfinity · Answer

what is n(Empty set)

xapproachesinfinity · Answer

vector yes the number of elements within the set

anonymous · Answer

@Vecters yes

@xapproachesinfinity that would probably be defined to be $0$.

xapproachesinfinity · Answer

oh a definition i see

vecters · Answer

So my answer would be 12 members right?

anonymous · Answer

Right, $n(U)=12$ because it's exactly the first $12$ natural numbers.

vecters · Answer

Okay, i got it now, thanks!