C program to find whether the number is Armstrong number or not.

Posted by Mangesh on March 16, 2018

Description :

A number is said to be Armstrong number, if sum of the cubes of its digits is equal to the number itself.
Example: 153 = 1*1*1 + 5*5*5 + 3*3*3 = 1 + 125 + 27.

Logic :

We can divide the number by 10 and get the remainder, the remainder here is also the right hand side digit. then we can divide the quotient by 10 and get the next digit. we shall do this till we get 0 as quotient. we can multiply the digit thrice by itself to get it cube.

Program :

int armstrong(int num)
  int total=0,rem;
  while (num != 0)
      rem = num % 10;
      total = total + (rem*rem*rem);
      num = num / 10;
   return total;
int main()
   int num,check;
   printf("\nEnter a number:");
   check = armstrong(num);
   if(check == num)
      printf("\n%d is an Armstrong Number.",num);
      printf("\n%d is not an Armstrong Number.",num);

Output :

C program for armstrong number` tested in Turbo C 3.2

Written with from Mangesh.

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