Empty Set - Definition and Examples

An empty set, also called null set, is a set that has no elements. For example, the set of even numbers divisible by 3 is an empty set since there are no even numbers that will give a remainder of zero when divided by 3. 

More examples of empty sets

1. Let A be the set of numbers that are odd and even at the same time.

Since a number is always either even or odd, A = {}

2. Let B be the set of people who has a net worth equal to at least 1 trillion in US dollars.

As of this writing, no one on earth has a net worth of at least 1 trillion in US dollars. Therefore, B = ø

This set might not be empty though in the future!

3. Let C = {x/x is a prime number and 7 < x < 11}

The numbers between 7 and 11 are 8, 9, and 10 and none of these are prime numbers. Therefore, C = {}