# Count factorial numbers in given range

To count the number of factorial numbers in a given range, we need to first define what a factorial number is.

A factorial number is a positive integer that is the product of all positive integers less than or equal to itself. For example, 4! (read as "4 factorial") is equal to 4 x 3 x 2 x 1 = 24.

To count the number of factorial numbers in a given range, we can iterate through each integer in the range and check if it is a factorial number. To do this, we can calculate the factorial of each integer less than or equal to the square root of the maximum number in the range, and check if any of those factorials are in the range.

Here given code implementation process.

```
// C program
// Count factorial numbers in given range
#include <stdio.h>
//Count the number of factorials in given range
void count_factorial(int front, int back)
{
if (front > back)
{
//Transform into a valid range
count_factorial(back, front);
}
else
{
int result = 0;
//Define loop controlling variables
int counter = 1;
int factorial = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
{
//Calculate factorial
factorial = factorial * counter;
if (factorial >= front && factorial <= back)
{
//When factorial exist in range (front to back)
result++;
}
counter++;
}
printf("\n Factorial in range [%d,%d] is : %d", front, back, result);
}
}
int main()
{
//Test case
count_factorial(0, 200);
count_factorial(300, 1000);
count_factorial(1000, 2000);
count_factorial(0, 0);
count_factorial(1, 2);
count_factorial(6000, 0);
return 0;
}
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
/*
Java program
Count factorial numbers in given range
*/
class Factorials
{
//Count the number of factorials in given range
public void count_factorial(int front, int back)
{
if (front > back)
{
//Transform into a valid range
count_factorial(back, front);
}
else
{
int result = 0;
//Define loop controlling variables
int counter = 1;
int factorial = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
{
//Calculate factorial
factorial = factorial * counter;
if (factorial >= front && factorial <= back)
{
//When factorial exist in range (front to back)
result++;
}
counter++;
}
System.out.print("\n Factorial in range [" + front + "," + back + "] is : " + result);
}
}
public static void main(String[] args)
{
Factorials obj = new Factorials();
//Test case
obj.count_factorial(0, 200);
obj.count_factorial(300, 1000);
obj.count_factorial(1000, 2000);
obj.count_factorial(0, 0);
obj.count_factorial(1, 2);
obj.count_factorial(6000, 0);
}
}
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
//Include header file
#include <iostream>
using namespace std;
/*
C++ program
Count factorial numbers in given range
*/
class Factorials
{
public:
//Count the number of factorials in given range
void count_factorial(int front, int back)
{
if (front > back)
{
//Transform into a valid range
this->count_factorial(back, front);
}
else
{
int result = 0;
//Define loop controlling variables
int counter = 1;
int factorial = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
{
//Calculate factorial
factorial = factorial *counter;
if (factorial >= front && factorial <= back)
{
//When factorial exist in range (front to back)
result++;
}
counter++;
}
cout << "\n Factorial in range [" << front << "," << back << "] is : " << result;
}
}
};
int main()
{
Factorials obj = Factorials();
//Test case
obj.count_factorial(0, 200);
obj.count_factorial(300, 1000);
obj.count_factorial(1000, 2000);
obj.count_factorial(0, 0);
obj.count_factorial(1, 2);
obj.count_factorial(6000, 0);
return 0;
}
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
//Include namespace system
using System;
/*
C# program
Count factorial numbers in given range
*/
class Factorials
{
//Count the number of factorials in given range
public void count_factorial(int front, int back)
{
if (front > back)
{
//Transform into a valid range
count_factorial(back, front);
}
else
{
int result = 0;
//Define loop controlling variables
int counter = 1;
int factorial = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
{
//Calculate factorial
factorial = factorial * counter;
if (factorial >= front && factorial <= back)
{
//When factorial exist in range (front to back)
result++;
}
counter++;
}
Console.Write("\n Factorial in range [" + front + "," + back + "] is : " + result);
}
}
public static void Main(String[] args)
{
Factorials obj = new Factorials();
//Test case
obj.count_factorial(0, 200);
obj.count_factorial(300, 1000);
obj.count_factorial(1000, 2000);
obj.count_factorial(0, 0);
obj.count_factorial(1, 2);
obj.count_factorial(6000, 0);
}
}
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
<?php
/*
Php program
Count factorial numbers in given range
*/
class Factorials
{
//Count the number of factorials in given range
public function count_factorial($front, $back)
{
if ($front > $back)
{
//Transform into a valid range
$this->count_factorial($back, $front);
}
else
{
$result = 0;
//Define loop controlling variables
$counter = 1;
$factorial = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while ($factorial <= $back)
{
//Calculate factorial
$factorial = $factorial * $counter;
if ($factorial >= $front && $factorial <= $back)
{
//When factorial exist in range (front to back)
$result++;
}
$counter++;
}
echo "\n Factorial in range [". $front .",". $back ."] is : ". $result;
}
}
}
function main()
{
$obj = new Factorials();
//Test case
$obj->count_factorial(0, 200);
$obj->count_factorial(300, 1000);
$obj->count_factorial(1000, 2000);
$obj->count_factorial(0, 0);
$obj->count_factorial(1, 2);
$obj->count_factorial(6000, 0);
}
main();
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
/*
Node Js program
Count factorial numbers in given range
*/
class Factorials
{
//Count the number of factorials in given range
count_factorial(front, back)
{
if (front > back)
{
//Transform into a valid range
this.count_factorial(back, front);
}
else
{
var result = 0;
//Define loop controlling variables
var counter = 1;
var factorial = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
{
//Calculate factorial
factorial = factorial * counter;
if (factorial >= front && factorial <= back)
{
//When factorial exist in range (front to back)
result++;
}
counter++;
}
process.stdout.write("\n Factorial in range [" + front + "," + back + "] is : " + result);
}
}
}
function main()
{
var obj = new Factorials();
//Test case
obj.count_factorial(0, 200);
obj.count_factorial(300, 1000);
obj.count_factorial(1000, 2000);
obj.count_factorial(0, 0);
obj.count_factorial(1, 2);
obj.count_factorial(6000, 0);
}
main();
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
# Python 3 program
# Count factorial numbers in given range
class Factorials :
# Count the number of factorials in given range
def count_factorial(self, front, back) :
if (front > back) :
# Transform into a valid range
self.count_factorial(back, front)
else :
result = 0
# Define loop controlling variables
counter = 1
factorial = 1
# Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back) :
# Calculate factorial
factorial = factorial * counter
if (factorial >= front and factorial <= back) :
# When factorial exist in range (front to back)
result += 1
counter += 1
print("\n Factorial in range [", front ,",", back ,"] is : ", result, end = "")
def main() :
obj = Factorials()
# Test case
obj.count_factorial(0, 200)
obj.count_factorial(300, 1000)
obj.count_factorial(1000, 2000)
obj.count_factorial(0, 0)
obj.count_factorial(1, 2)
obj.count_factorial(6000, 0)
if __name__ == "__main__": main()
```

#### Output

```
Factorial in range [ 0 , 200 ] is : 5
Factorial in range [ 300 , 1000 ] is : 1
Factorial in range [ 1000 , 2000 ] is : 0
Factorial in range [ 0 , 0 ] is : 0
Factorial in range [ 1 , 2 ] is : 2
Factorial in range [ 0 , 6000 ] is : 7
```

```
# Ruby program
# Count factorial numbers in given range
class Factorials
# Count the number of factorials in given range
def count_factorial(front, back)
if (front > back)
# Transform into a valid range
self.count_factorial(back, front)
else
result = 0
# Define loop controlling variables
counter = 1
factorial = 1
# Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
# Calculate factorial
factorial = factorial * counter
if (factorial >= front && factorial <= back)
# When factorial exist in range (front to back)
result += 1
end
counter += 1
end
print("\n Factorial in range [", front ,",", back ,"] is : ", result)
end
end
end
def main()
obj = Factorials.new()
# Test case
obj.count_factorial(0, 200)
obj.count_factorial(300, 1000)
obj.count_factorial(1000, 2000)
obj.count_factorial(0, 0)
obj.count_factorial(1, 2)
obj.count_factorial(6000, 0)
end
main()
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
/*
Scala program
Count factorial numbers in given range
*/
class Factorials
{
//Count the number of factorials in given range
def count_factorial(front: Int, back: Int): Unit = {
if (front > back)
{
//Transform into a valid range
count_factorial(back, front);
}
else
{
var result: Int = 0;
//Define loop controlling variables
var counter: Int = 1;
var factorial: Int = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
{
//Calculate factorial
factorial = factorial * counter;
if (factorial >= front && factorial <= back)
{
//When factorial exist in range (front to back)
result += 1;
}
counter += 1;
}
print("\n Factorial in range [" + front + "," + back + "] is : " + result);
}
}
}
object Main
{
def main(args: Array[String]): Unit = {
var obj: Factorials = new Factorials();
//Test case
obj.count_factorial(0, 200);
obj.count_factorial(300, 1000);
obj.count_factorial(1000, 2000);
obj.count_factorial(0, 0);
obj.count_factorial(1, 2);
obj.count_factorial(6000, 0);
}
}
```

#### Output

```
Factorial in range [0,200] is : 5
Factorial in range [300,1000] is : 1
Factorial in range [1000,2000] is : 0
Factorial in range [0,0] is : 0
Factorial in range [1,2] is : 2
Factorial in range [0,6000] is : 7
```

```
/*
Swift 4 program
Count factorial numbers in given range
*/
class Factorials
{
//Count the number of factorials in given range
func count_factorial(_ front: Int, _ back: Int)
{
if (front > back)
{
//Transform into a valid range
self.count_factorial(back, front);
}
else
{
var result: Int = 0;
//Define loop controlling variables
var counter: Int = 1;
var factorial: Int = 1;
//Execute the loop until the resulting factorial not exceeds the given limit
while (factorial <= back)
{
//Calculate factorial
factorial = factorial * counter;
if (factorial >= front && factorial <= back)
{
//When factorial exist in range (front to back)
result += 1;
}
counter += 1;
}
print("\n Factorial in range [", front ,",", back ,"]is : ", result, terminator: "");
}
}
}
func main()
{
let obj: Factorials = Factorials();
//Test case
obj.count_factorial(0, 200);
obj.count_factorial(300, 1000);
obj.count_factorial(1000, 2000);
obj.count_factorial(0, 0);
obj.count_factorial(1, 2);
obj.count_factorial(6000, 0);
}
main();
```

#### Output

```
Factorial in range [ 0 , 200 ]is : 5
Factorial in range [ 300 , 1000 ]is : 1
Factorial in range [ 1000 , 2000 ]is : 0
Factorial in range [ 0 , 0 ]is : 0
Factorial in range [ 1 , 2 ]is : 2
Factorial in range [ 0 , 6000 ]is : 7
```

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