bigFactorial.cpp

#include<bits/stdc++.h> 
using namespace std; 

#define MAX 200 

int multiply(int x, int res[], int res_size) { 
    
    int carry = 0; 

    for (int i=0; i<res_size; i++) { 

        int prod = res[i] * x + carry; 

        res[i] = prod % 10;   
  
        carry  = prod/10;     
    } 
  
    while (carry) { 

        res[res_size] = carry%10; 
        carry = carry/10; 
        res_size++; 

    } 

    return res_size; 
    
} 

void factorial(int n) { 

    int res[MAX]; 
  
    res[0] = 1; 
    int res_size = 1; 
  
    for (int x=2; x<=n; x++) 
        res_size = multiply(x, res, res_size); 

  
    cout << "Factorial of given number is \n"; 
    for (int i=res_size-1; i>=0; i--) 
        cout << res[i]; 
} 
  


int main() { 

    factorial(100); 

    return 0; 

}