#include<fstream>
#include<iostream>
using namespace std;
char sir[100];
int calc (int uc)
{int x=1;
	for(int i=1;i<=uc;i++)
	x=(x*uc)%10;
return x;
}
int main()
{double start=clock();
	int t,i,a,b,x,suma,d,uc;
ifstream f1("cifra.in");
ofstream f2("cifra.out");
f1>>t;
for(i=1;i<=t;++i)
{f1>>sir;
a=sir[strlen(sir)-1]-48;
if(sir[strlen(sir)-2]) b=sir[strlen(sir)-2]-48;
else b=0;
x=b*10+a;
suma=0;

for(d=1;d<=x;d++)
	{uc=d%10;
	
	suma=(suma+calc(uc))%10;
	}
f2<<suma<<'\n';
}
double stop=clock();
cout<<(stop-start)/CLOCKS_PER_SEC;
return 0;
}