- (i)
- means that is the set whose elements are the letter , the digit , the symbols and the asterisk .
- (ii)
- is a positive even number is the set of all even natural numbers. We could have defined the set using the following notation , but it is impossible to write down a complete list.

- The order of the elements in the list is irrelevant. The notations and denote the same set.
- If an element is listed more than once, it counts for one element only. For example, is the same set s .

- (i)
- The domain of definition of the expression is empty, as has to be not less than 3 and not more than 1 at the same time.
- (ii)
- The set of real solutions of a quadratic equation with real coefficients is empty whenever the discriminant is negative.
- (iii)
- The set of sixteen feet high gnus is empty.