PHP Program to Check Strong Number

Posted in PHP Tutorial

Updated on Jan 11, 2024

By Mari Selvan

👁️ 106 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the world of programming, exploring number properties is a fascinating journey. One such property is related to Strong Numbers.

A Strong Number (also known as a Digital Factorial) is a number in which the sum of the factorials of its digits is equal to the number itself.

In this tutorial, we'll delve into a PHP program that checks whether a given number is a Strong Number or not.

📄 Example

Let's take a look at the PHP code that checks whether a given number is a Strong Number.

isStrongNumber.php

Copied

<?php
// Function to calculate the factorial of a number
function factorial($num)
{
  if ($num == 0 || $num == 1)
  {
    return 1;
  }
  else
  {
    return $num * factorial($num - 1);
  }
}

// Function to check if a number is a Strong Number
function isStrongNumber($num)
{
  $originalNum = $num;
  $sum = 0;

  while ($num > 0)
  {
    $digit = $num % 10;
    $sum += factorial($digit);
    $num = (int)($num / 10);
  }

  return ($sum == $originalNum);
}

// Replace this value with your desired number
$number = 145;

// Call the function to check if the number is a Strong Number
if (isStrongNumber($number))
{
  echo "$number is a Strong Number.\n";
}
else
{
  echo "$number is not a Strong Number.\n";
}

?>

💻 Testing the Program

To test the program with different numbers, simply replace the value of $number in the code.

Output

145 is a Strong Number.

Run the script to check if the number is a Strong Number.

🧠 How the Program Works

The program defines a function factorial to calculate the factorial of a number.
Another function isStrongNumber is defined to check if a given number is a Strong Number.
Inside the isStrongNumber function, it iterates through each digit of the number, calculates the factorial, and adds it to the sum.
The result is compared with the original number to determine if it is a Strong Number.

📏 Between the Given Range

Let's take a look at the php code that checks for strong numbers in the range of 1 to 200.

isStrongNumber.php

Copied

<?php
// Function to calculate the factorial of a number
function factorial($num)
{
  if ($num == 0 || $num == 1)
  {
    return 1;
  }
  else
  {
    return $num * factorial($num - 1);
  }
}

// Function to check if a number is a strong number
function isStrongNumber($num)
{
  $originalNum = $num;
  $sum = 0;

  while ($num > 0)
  {
    $digit = $num % 10;
    $sum += factorial($digit);
    $num = (int)($num / 10);
  }

  return $sum == $originalNum;
}

// Driver program
echo "Strong Numbers in the Range 1 to 200:\n";

for ($i = 1;$i <= 200;$i++)
{
  if (isStrongNumber($i))
  {
    echo $i . " ";
  }
}

?>

💻 Testing the Program

Output

Strong Numbers in the Range 1 to 200:
1 2 145

Run the script to see the strong numbers in the specified range.

🧠 How the Program Works

The program defines a factorial function to calculate the factorial of a given number.
It then defines an isStrongNumber function that checks if a number is a strong number by summing the factorials of its digits.
The main section iterates through numbers from 1 to 200, checking and printing those that are strong numbers.

🧐 Understanding the Concept of Strong Number

To determine if a number is a Strong Number, we need to calculate the factorial of each digit of the number and then sum these factorials. If the sum is equal to the original number, then it is a Strong Number.

For example, let's consider the number 145:

The factorial of 1 is 1.
The factorial of 4 is 24.
The factorial of 5 is 120.

The sum of these factorials is 1 + 24 + 120 = 145, which is the original number. Hence, 145 is a Strong Number.

🎉 Conclusion

Understanding and implementing programs that check for mathematical properties, such as Strong Numbers, enhances problem-solving skills in programming. Feel free to modify and expand upon this code for your specific needs. Happy coding!