Cardinality of $A = \varnothing, B = \{ \varnothing \}, C = \{\{\varnothing\}\}$ Given three sets $A = \varnothing, B = \{ \varnothing \}, C = \{\{\varnothing\}\}$ what are the cardinalities of those sets ?
Obviously cardinality of $A$ is $0$ and cardinality of $B$ is $1$, but I am not sure about set $C$, because some sources say that cardinality of such set is $2$. Can you please clarify this to me ?

$$A = \varnothing, B = \{ \varnothing \}, C = \{\{\varnothing\}\}$$
The way  you have it $B$ and $C$ both have cardinality of $1$
My guess is that you wanted  $$C = \{ \varnothing ,\{\varnothing\}\}$$
Which has cardinality $2$.
