You can prove that a statement is not true by using a counter example. All you have to do is find just one example which does not work for the statement.

Disproof by counter example involves:

• Find one example that does not work for the statement to be disproved.
• You don't have to give more than one example, as one is sufficient to disprove a statement.

Example 1

Prove that the following statement is not true:

The sum of two consecutive prime numbers is always even.

$2$ and $3$ are both prime.

$2+3=5$

$5$ is odd.

Therefore the statement is not true.