In this tutorial, we are going to write an **algorithm to verify whether a number is prime or not**. using this algorithm we can write a **program to verify whether a number is prime or not** or **find whether a number is prime or not** in most programming languages like java, python, c++, and c.

## Algorithm to find Prime Number.

**1. Read N.**

**2. Set I:=2 and PRIME = 1.**

**3. Repeat Steps 4 to 7 while I <= N/2**

**4. If(N % I=0)**

**5. Set PRIME:=0. and exit the loop structure.**

**6. Else:**

**7. Set I:=I + 1.**

**8. [End of If Structure.]**

**9. [End of While loop]**

**10. If PRIME = 1, then:**

**11. Print the number is prime.**

**12. Else**

**13. Print the number is not prime.**

**14. [End of If structure.]**

**15. Exit.**

Here in the above algorithm, we first read an integer variable N. and then set default values of two variables I=2 and PRIME = 1 and then using the while loop we repeat steps 4 to 7. in the if condition we check if the value of N is divisible by 2 then we set the value of PRIME to 0 and exit from the loop else we set the value of I to I + 1. this process is executed till the value of I less than or equal to N/2. then we check if the value of the PRIME variable is 1 then we print the number is prime else we print the number as not prime. and then we exit from the program.

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