C Example Factorial Number

What is factorial? Factorial of a number n (written as n!) is the product of all positive integers from 1 to n.

In Real world factorial using in multiple areas as follows

Scheduling & Resource Allocation: Arranging tasks, machines, or workers in different possible orders.
Cryptography: Large factorial numbers help in generating complex keys.
Data Science / Machine Learning: Factorial-based combinations used in probability distributions (Binomial, Poisson).
Gaming / Puzzle Design: Number of ways to shuffle cards (52! possible ways). Sudoku arrangement possibilities.
Engineering / Reliability Analysis: Calculating probabilities of system failures (when multiple components work together).

n! = n

0 = 1  
1 = 1  
2 = 2  
3 = 6  
4 = 24  
5 = 120  
6 = 720  
7 = 5.040  
8 = 40.320  
9 = 362.880  
10 = 3.628.800  
11 = 39.916.800  
12 = 479.001.600

C Program to Find Factorial of a Number

Please refer: https://github.com/aruneworld/Computer_Programming/blob/master/C/Examples/Factorial.c

Example Code 1:

C code for factorial of a number
C program to find the factorial of a given number
Factorial program in c using while loop
 Factorial program in c without using recursion

#include<stdio.h> 
int main()
{ 
  int i=1,f=1,num; 
  printf("C Example Factorial Number");
  printf("Enter a number: "); 
  scanf("%d",&num); 
  while(i<=num)
 { 
      f=f*i; 
      i++; 
  } 
   printf("Factorial of %d is: %d",num,f); 
  return 0; 
} 
/*
Sample output: 
Enter a number: 5 
Factorial of 5 is: 120 
*/

Explanation:

f=f*i; → multiplies the current result with i each time.
while(i<=num) ensures multiplication continues until all numbers from 1 to num are covered.
f starts with 1 because multiplying by 0 would always give 0.
If you enter 0, the loop won’t run, so f remains 1 → which matches the definition 0! = 1.

Code 2:

Factorial program in c using for loop
Simple factorial program in c
C program to calculate factorial

#include<stdio.h> 
int main()
{ 
  int i,f=1,num; 
  printf("Enter a number: "); 
  scanf("%d",&num); 
  for(i=1;i<=num;i++) 
      f=f*i; 
  printf("Factorial of %d is: %d",num,f); 
  return 0; 
}

Example Code 3:

Factorial program in c using pointers
How to calculate factorial in c
Factorial program in c language

#include<stdio.h> 
void findFactorial(int,int *); 
int main()
{ 
  int i,factorial,num; 
  printf("Enter a number: "); 
  scanf("%d",&num); 
  findFactorial(num,&factorial); 
  printf("Factorial of %d is: %d",num,*factorial); 
  return 0; 
} 

void findFactorial(int num,int *factorial)
{ 
    int i; 
    *factorial =1; 
    for(i=1;i<=num;i++) 
      *factorial=*factorial*i; 
}

Code 4:

Factorial program in c using function
C program to find factorial of a number

#include<stdio.h> 
int findFactorial(int); 
int main()
{ 
  int i,factorial,num; 
 printf("Enter a number: "); 
  scanf("%d",&num); 
  factorial = findFactorial(num); 
  printf("Factorial of %d is: %d",num,factorial); 
  return 0; 
} 
int findFactorial(int num)
{ 
   int i,f=1; 
    for(i=1;i<=num;i++) 
      f=f*i; 
     return f; 
}
/*
Sample output: 
Enter a number: 8 
Factorial of 8 is: 40320 
*/

Code 5: Factorial series in c

#include<stdio.h> 
int main()
{ 
  long f=1; 
  int i,num,min,max; 
  printf("Enter the minimum range: "); 
  scanf("%d",&min); 
  printf("Enter the maximum range: "); 
  scanf("%d",&max); 
  printf("Factorial series in given range: "); 
  for(num=min;num<=max;num++){ 
    f=1; 
    for(i=1;i<=num;i++) 
      f=f*i; 
    printf("%ld ",f); 
  } 
  return 0; 
}
/*
Sample output: 
Enter the minimum range: 1 
Enter the maximum range: 10 
Factorial series in given range: 1 2 6 24 120 720 5040 40320 362880 3628800 
*/

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