Broken calculator

#1

this is the code
#include
using namespace std;

int multiply( int *res, int x, int res_size)
{

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

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;
}

int main() {
int n;
int res[500];
int res_size=1,x,i;
res[0]={1};
cin>>n;
if(n==1)
cout<<“1”;
else
{

for (x=2;x<=n;x++)
res_size=multiply( res, x,res_size);
for (i=res_size-1;i>=0;i–)
cout<<res[i];
}

return 0;

}
this is the code i found but i honestly do not understand how it works so please explain

#2

Change the size of res array to 2000

#3

Bro I am not asking why this code is not passing test cases. I am asking I don’t understand how this works please explain

#4

The answer of 500 factorial has more than 500 digits, so you need to increase the size of your res array to prevent overflow.

#5

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