# C Program to Check Whether a Number is Prime or Not

## Write C Program to find number is Prime number or not.

In this program we will find a number is a prime number or not with the help of for loop or if else statement. A number is considered as prime number when it satisfies the below conditions.

• Prime number is a number which can be divided by 1 and itself
• A number which can not be divided by any other number other than 1 or itself is a prime number.
• It should have only 2 factors. They are, 1 and the number itself.

Ex- Number is 13. it have only 2 factor

• it is divisible by 1.
• And it is divisible by itself

So it is a prime number ### Working:-

Step 1.Read a “num” value to check prime or not.
Step 2.set i=1,div=0.
Step 3.if i<=num if true go to step 4, else go to step 7.
Step 4.Check the condition num%i==0 if true then evaluate step 5, else go to step 6.
Step 5.set div=div+1
Step 6.i=i+1, go to step 4
Step 7.check div, if div==2 display prime, else display not prime
Step 8.Stop

### C Program:-

`#include<stdio.h>int main(){      //initializing variables      int c,number,div=0;      //user input      printf("Enter number: ");       scanf("%d",&number);       //checking for number of divisor      for(c=1;c<=number;c++)       {           if(number%c==0)           {                div++;             }      }      //no divisors other than 1 and itself       if(div==2)        {           //display            printf("%d is a prime number",number);       }       else       {           //display            printf("%d is not a prime number",number);       }    return 0;}`

### Output:-

`Enter number:66 is not a prime numberEnter number:1313 is a prime number`