In the set-builder notation (rule method),the null set is represented by:

Let $S = \{ 0, 1, 5, 4, 7 \}$. Then the total number of subsets of $S$ is

Two sets $A$ and $B$ are disjoint if and only if

Match each of the set on the left described in the roster form with the same set on the right described in the set-builder form:

$(i) \{ P,R,I,N,C,A,L\} $	$(a) \{ x:x \text{ is a positive integer and is a divisor of } 18\} $
$(ii) \{ 0\} $	$(b) \{ x:x \text{ is an integer and } x^2 - 9 = 0\} $
$(iii) \{ 1,2,3,6,9,18\} $	$(c) \{ x:x \text{ is an integer and } x + 1 = 1\} $
$(iv) \{ 3, -3\} $	$(d) \{ x:x \text{ is a letter of the word } PRINCIPAL\} $

Make correct statements by filling in the symbols $\subset$ or $\not\subset$ in the blank spaces:
${ x:x \text{ is an even natural number} } \dots { x:x \text{ is an integer} }$

If $y = 3[x] + 1 = 4[x - 1] - 10$,then $[x + 2y]$ is equal to (where $[.]$ is the $Greatest$ $Integer$ $Function$)