Check Strong Number in C, C++, Java & Python – Code with Explanation & Examples in Short and Simple

   

C Program

int fact(int n) {
    int f = 1;
    for (int i = 2; i <= n; i++) f *= i;
    return f;
}

int isStrong(int n) {
    int sum = 0, x = n;
    while (x) {
        sum += fact(x % 10);
        x /= 10;
    }
    return sum == n;
}

C Output

Input:  
145  

Output:  
Yes, Strong Number

C++ Program

int fact(int n) {
    int f = 1;
    for (int i = 2; i <= n; i++) f *= i;
    return f;
}

bool isStrong(int n) {
    int sum = 0, x = n;
    while (x) {
        sum += fact(x % 10);
        x /= 10;
    }
    return sum == n;
}

C++ Output

Input:  
145  

Output:  
true

JAVA Program

int fact(int n) {
    int f = 1;
    for (int i = 2; i <= n; i++) f *= i;
    return f;
}

boolean isStrong(int n) {
    int sum = 0, x = n;
    while (x > 0) {
        sum += fact(x % 10);
        x /= 10;
    }
    return sum == n;
}

JAVA Output

Input:  
145 

Output:  
true

Python Program

def is_strong(n):
    return n == sum(__import__('math').factorial(int(d)) for d in str(n))

Python Output

Input:  
145

Output:  
True

Explanation in Detail

Example

Consider number 145.

Divide it into digits: 1, 4, and 5

Now, find the factorial of each digit:

1! = 1

4! = 24

5! = 120

Add them: 1 + 24 + 120 = 145

Because the sum is the same as the original number, 145 is a Strong Number.

Analogy to Real Life

Imagine a magical lock which only opens when each digit's "power value" (in this case, factorial) adds up to just enough to reproduce the original code. If all the components (digits) cooperate perfectly with their factorial power, you have a match — a "Strong" identity.

It's similar to a group where every member gives everything (factorial effort), and their total contribution is exactly what the team requires — nothing more, nothing less.

Why It Matters

Strong Numbers are interesting as they combine digit manipulation with factorial reasoning — two core aspects of programming. It's an excellent exercise in:

Looping

Modular arithmetic

Factorial calculations

Conditional checks

It's also helpful to build logic for digit-based pattern problems in competitive coding and interviews.

What You Learn from This

You acquire hands-on experience in:

Breaking numbers into digits using modulo and division

Writing or employing a factorial function

Awareness of mathematical properties of numbers

Applying conditions to test number patterns

It strengthens both mathematics in thinking and loop-based programming, enabling you to address similar problems such as Armstrong numbers, Palindromes, or Krishnamurthy numbers.

Interview Relevance and Real Projects

This question is commonly asked in:

College viva or evaluations

Logic-building phases of coding interviews

Pattern identification in algorithm tests

In real-world use, such problems are useful in:

Validation systems

Mathematical apps or games

Competitive programming sites like HackerRank or Codeforces

Interviewers usually apply this to observe how you:

Work with digits

Optimize repetitive calculations

Think mathematically in code

SEO-Optimized Explanation

Checking whether a number is a Strong Number in C, C++, Java, or Python involves computing the sum of factorials of its digits and comparing it to the original number. It’s a classic beginner problem that strengthens skills in digit extraction, factorial calculation, loops, and conditional logic. This concept is widely used in programming interviews and coding competitions. With real-world usage in math puzzles and number theory games, Strong Numbers also establish the foundation for higher-level algorithmic thought. Mastering this improves your logical thinking and prepares you for digit analysis and mathematical proof questions in real-world programs.