Useful programs

C   Armstrong Number programs

Before going to write the c program to check whether the number is Armstrong or not, let’s understand what is Armstrong number.

Armstrong number is a number that is equal to the sum of cubes of its digits. For example 0, 1, 153, 370, 371 and 407 are the Armstrong numbers.

Let’s try to understand why 153 is an Armstrong number.

153 = (1*1*1)+(5*5*5)+(3*3*3) 
where: 
(1*1*1)=1 
(5*5*5)=125 
(3*3*3)=27 
So: 
1+125+27=153 

Example

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

Output:


enter the number=153
armstrong number