# Some Programs in C

**1. Write a program to check whether the given number is prime or not**

**Prime Number –** Prime numbers are those numbers which has no positive divisor other than 1 and itself.

**Example**

#include<stdio.h> int main() { int i,n,p=0; printf("enter the number"); scanf("%d",&n); for(i=2;i<n;i++) { if(n%i==0) { p=1; break; } } if(p==0) { printf("Number is prime"); } else { printf("Number is not prime"); } return 0; }

**Output**

enter the number 17

Number is prime

**2. Write a program to calculate the Factorial.**

**Factorial – **It is the product of all positive integers less than or equal to *n*. It is denoted by n!.

**Example**

#include<stdio.h> int main() { int i,n,f=1; printf("enter the number"); scanf("%d",&n); for(i=1;i<=n;i++) { f=f*i; } printf("Factorial of number is=%d",f); }

**Output**

enter the number 5

Factorial of number is=120

**3. Write a program to check whether the given number is palindrome or not.**

**Palindrome Number –** Palindrome numbers are those numbers which reads the same backward or forward.

**Example**

#include<stdio.h> int main() { int r,n,p=0,temp; printf("enter the number"); scanf("%d",&n); temp=n; while(n!=0) { r=n%10; p=p*10+r; n=n/10; } if(p==temp) { printf("Number is palindrome"); } else { printf("Number is not palindrome"); } return 0; }

**Output**

enter the number 111

number is palindrome

**4. Write a program to check whether the number is Armstrong or not.**

**Armstrong Number –** Armstrong number is an integer such that the sum of the cubes of its digits is equal to the number itself.

**Example**

#include<stdio.h> int main() { int n,r,p=0,temp; printf("enter the number "); scanf("%d",&n); temp=n; while(n>0) { r=n%10; p=p+(r*r*r); n=n/10; } if(temp==p) { printf("Number is Armstrong"); } else { printf("Number is not Armstrong"); } return 0; }

**Output**

enter the number 153

Number is Armstrong

**5. Write a program to display the Fibonacci Series.**

**Fibonacci Series –** A series in which next number is occurred by adding two previous numbers.

**Example**

#include<stdio.h> int main() { int i=0,j=1,k,p,n; printf("Enter the number of elements:"); scanf("%d",&n); printf("\n%d %d",i,j); for(p=2;p<n;++p)//loop starts from 2 because 0 and 1 are already printed { k=i+j; printf(" %d",k); i=j; j=k; } return 0; }

**Output**

Enter the number of elements:12

0 1 1 2 3 5 8 13 21 34 55 89

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