1. Check whether the language is **finite** or not. If its finite then it is surely **regular.**

2. If its not finite then there may be a case that its not regular.

3. Rules for checking if regular:

a) Check if there is any pattern in **AP** then its regular.

b) If there is any irregular pattern like in **GP** or in terms of prime then not regular.

c) If automaton requires saving of **infinite length** string then comparing then its not regular.

d) **Modular counting or modular** division is always **regular**.

4) **Pumping Lemma is negativity test** means

a) **If passed then language may or may not be regular**.

b) **If failed then language is definitely not regular.**