How to find factorial of large number in c++?

Question

Factorial of number even unsigned long long int can hold

Answer 1

#include<iostream>

using namespace std;

int multiply(int x,int a[],int size)
{
int carry=0,i,p;

for(i=0;i<size;++i)
{
p=a[i]*x+carry;
a[i]=p%10;
carry=p/10;
}

while(carry!=0)
{
a[size]=carry%10;
carry=carry/10;
size++;
}
return size;
}

int main()
{
int n,a[1000],i,size=1;
a[0]=1;

cout<<"Enter any large number:";
cin>>n;

for(i=2;i<=n;++i) {
size=multiply(i,a,size);
}

for(i=size-1;i>=0;--i)
{
cout<<a[i];
}

return 0;
}

Answer 2

I built a really big number arithmetic processor where a number was treated as a number but stored as a string. It could do math with 2000 + digits, and maybe much more.

Answer 3

!!!!!