Question

Write program to find whether the given number is strong number or not.

Answer 1

Write a C program to input number from user and check whether number is Strong number or not. How to check strong numbers using loop in C programming. Logic to check strong number in C programming.

Example

Input

Input number: 145

Output

145 is STRONG NUMBER

Required knowledge

Basic C programming, If else, For loop, While loop, Nested loop

What is Strong number?

Strong number is a special number whose sum of factorial of digits is equal to the original number.
For example: 145 is strong number. Since, 1! + 4! + 5! = 145

Logic to check Strong number

Step by step descriptive logic to check strong number.

Input a number from user to check for strong number. Store this in a variable say num. Copy it to a temporary variable for calculations purposes, say originalNum = num.

Initialize another variable to store sum of factorial of digits, say sum = 0.

Find last digit of the given number num. Store the result in a variable say lastDigit = num % 10.

Find factorial of lastDigit. Store factorial in a variable say fact.

Add factorial to sum i.e. sum = sum + fact.

Remove last digit from num as it is not needed further.

Repeat steps 3 to 6 till num > 0.

After loop check condition for strong number. If sum == originalNum, then the given number is Strong number otherwise not.

Learn more - Program to find sum of digits of number.

Program to check Strong number

/** * C program to check whether a number is Strong Number or not */ #include <stdio.h> int main() { int i, originalNum, num, lastDigit, sum; long fact; /* Input a number from user */ printf("Enter any number to check Strong number: "); scanf("%d", &num); /* Copy the value of num to a temporary variable */ originalNum = num; sum = 0; /* Find sum of factorial of digits */ while(num > 0) { /* Get last digit of num */ lastDigit = num % 10; /* Find factorial of last digit */ fact = 1; for(i=1; i<=lastDigit; i++) { fact = fact * i; } /* Add factorial to sum */ sum = sum + fact; num = num / 10; } /* Check Strong number condition */ if(sum == originalNum) { printf("%d is STRONG NUMBER", originalNum); } else { printf("%d is NOT STRONG NUMBER", originalNum); } return 0; }

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