Strong Number Program in C

June 29, 2023

Strong number in C

In this program we will find whether a number is strong number in C programming. A Strong Number is a number whose sum of factorial digits is equal to the number itself.

Ex:- number is 145

1! + 4! + 5! = 145 

So it is a strong number.

Methods discussed

Method 1 iterative way of calculation of factorial
Method 2 recursive way of calculation of factorial

Method 1

For input num

Fetch individual digits of the number
Calculate factorial of each individual digit and add them
If sum == num then its strong
Else its not strong number

C Program:-

Run

#include <stdio.h>

// function to calculate factorial
int getFactorial(int n){
    int fact = 1;
    
    for(int i = 1; i <= n; i++)
            fact = fact * i;
    
    return fact;
}

int checkStrong(int num){
    
    int digit, sum = 0;
    int temp = num;
    
    // calculate 1! + 4! + 5!
    while(temp!=0){
        digit = temp % 10;
        
        sum = sum + getFactorial(digit);
        temp /= 10;
    }
    
    // returns 1 if both equal else 0
    return sum == num;
    
}
int main ()
{
    int num = 145;
    
    if(checkStrong(num))
        printf("%d is Strong Number", num);
    else
        printf("%d is Not Strong Number", num);

}
// Time complexity: O(N^2)
// Space complexity: O(1)

Output:-

145 is Strong Number

Factor of a number

Finding Prime Factors of a number

Strong number

Perfect number

Perfect Square

Automorphic number

Method 2

In this method, we will use a recursive way to calculate the factorial number.

For input num

Fetch individual digits of the number
Calculate factorial (using Recursion) of each individual digit and add them
If sum == num then its strong
Else its not strong number

C Program:-

Run

#include <stdio.h>

// function to calculate factorial
int getFactorial(int num)
{
    if(num == 0)
        return 1;
        
    return num * getFactorial(num-1);
}

int checkStrong(int num){
    
    int digit, sum = 0;
    int temp = num;
    
    // calculate 1! + 4! + 5!
    while(temp!=0){
        digit = temp % 10;
        
        sum = sum + getFactorial(digit);
        temp /= 10;
    }
    
    // returns 1 if both equal else 0
    return sum == num;
    
}
int main ()
{
    int num = 145;
    
    if(checkStrong(num))
        printf("%d is Strong Number", num);
    else
        printf("%d is Not Strong Number", num);

}
// Time complexity: O(N^2)
// Space complexity: O(1)
// Auxialiary Space complexity: O(N) bcz of function call stack

Output:-

145 is Strong Number

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Strong Numbers in a given Range

C Program:-

Run

#include <stdio.h>  
int main()  
{  
    int n = 100000;
    
    printf("\nStrong numbers in range 1 to %d :\n", n);  
    for(int i=1;i<=n;i++)  
    {
        int sum = 0, digit;
        int num = i;  
        while(num != 0)  
        {  
            digit = num % 10;  
            int fact = factorial(digit);  
             
          
            num = num/10;  
            sum = sum + fact;  
        }  
        
        if(sum == i){
            printf("%d, ",i);
        }  
    }
    return 0;  
}

int factorial(int n){  
    int mul = 1;
    
    for(int i = 1; i <= n; i++)  
        mul = mul * i;  

    return mul;  
}

Output:-

Strong numbers in range 1 to 100000 :
1, 2, 145, 40585,

Positive or Negative number: C | C++ | Java | Python
Even or Odd number: C | C++ | Java | Python
Sum of First N Natural numbers: C | C++ | Java | Python
Sum of N natural numbers: C | C++ | Java | Python
Sum of numbers in a given range: C | C++ | Java | Python
Greatest of two numbers: C | C++ | Java | Python
Greatest of the Three numbers: C | C++ | Java | Python
Leap year or not: C | C++ | Java | Python
Prime number: C | C++ | Java | Python
Prime number within a given range: C | C++ | Java | Python
Sum of digits of a number: C | C++ | Java | Python
Reverse of a number : C | C++ | Java | Python
Palindrome number: C | C++ | Java | Python
Armstrong number : C | C++ | Java | Python
Armstrong number in a given range : C | C++ | Java | Python
Fibonacci Series upto nth term : C | C++ | Java | Python
Find the Nth Term of the Fibonacci Series : C | C++ | Java | Python
Factorial of a number : C | C++ | Java | Python
Power of a number : C | C++ | Java | Python
Factor of a number : C | C++ | Java | Python
Strong number : C | C++ | Java | Python
Perfect number : C | C++ | Java | Python
Automorphic number : C | C++ | Java | Python
Harshad number : C | C++ | Java | Python
Abundant number : C| C++ | Java | Python
Friendly pair : C | C++ | Java | Python

5 comments on “Strong Number Program in C”

Starboyy
#include

int main()
{
int number = 145;
int temp=number;
int product=1;
int sum=0;
while(number!=0)
{
int remainder = number % 10;
for(int i=1;i<=remainder;i++)
{
product=product*i;
}
sum=sum+product;
product=1;
number =number/10;
}

if(sum==temp)
{
printf("strong number ");
}
else{
printf("Weak numebr");
}
}

0

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rabin
#python_code_of_strong_number
import math
num=int(input(“:”))
temp=num
sum=0
while num>0:
digit=int(num%10)
num=num//10
x=math.factorial(digit)
sum=sum+x

if temp==sum:
print(“strong number”)
else:
print(“not strong”)

0

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Srikanth
# strong number
from math import factorial
num=int(input(“Enter a number : “))
temp = num
total = 0
while num > 0:
dig=num % 10
num=num//10
a=factorial(dig)
total = total + a
if total==temp:
print(f”the given number {temp} is a strong number “)
else:
print(f”the given number {temp} is not a strong number “)

1

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Mohammed Monis
Strong number for Python :
Code :-
num = int(input(“Enter a number : “))
temp = num
num = [int(d) for d in str(num)]

strng_n = 0

def fact(n):
factorial = 1
for i in range(1, n+1):
factorial = factorial * i
return factorial

for i in range(0, len(num)):
strng_n = strng_n + fact(num[i])

if temp == strng_n:
print(“It is a strong number”)
else:
print(“It is not a strong number”)

0

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Archibrata
Python Solution
import math
a = int(input())
summ = 0
l = [int(d) for d in str(a)]
for i in l:
summ+=(math.factorial(i))
if summ == a:
print(“strong”)
else:
print(“not”)

0

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