How to check whether it is prime number or not ?

Answer 1

https://en.wikipedia.org/wiki/Primality_test

Answer 2

Use the search function xd
- Go to code section
- Type prime no. In search bar
- Choose language as c
- You will find some result
- It will easy the job of yours if you dont want to try
- If you have try then show us your try we would love to help :p