Armstrong number is an integer which has sum of cubes of its individual digits equal to the number itself.

**Example:** 0,1,153,370,..

## logic

- Seperate each digit of input integer and then calculate its cube.
- Add the cube of all digits
- check final sum against input integer

## Program

### program to check armstrong number using recursive function or recursion

```
#include<stdio.h>
#include<conio.h>
int armstrong(int num);
void main()
{
int num, n;
printf("n Enter a number: ");
scanf("%d", &num);
n = armstrong(num);
printf("n %d is armstrong number",n);
getch();
}
int armstrong(int num)
{
int s = 0;
if(num)
{
s = ((num%10)*(num%10)*(num%10)) + armstrong(num/10);
}
return s;
}
```

### Output

```
input = 407
output = (4*4*4) + (0*0*0) + (7*7*7)
input number equals sum of cube of all its digits.
So 407 is armstrong number
```