#include<fstream.h>
#include<string.h>
int r[4][10]={ {0,1,2,3,4,5,6,7,8,9},
	       {0,1,4,9,6,5,6,9,4,1},
	       {0,1,8,7,4,5,6,3,2,9},
	       {0,1,6,1,6,5,6,1,6,1}
	       };
int main()
{ifstream f("cifra.in");
ofstream g("cifra.out");
char n[102];
int t,j,i,s,m,n1,p,c,k,q;
f>>t;
for(j=1;j<=t;j++)
{
f>>n;
m=strlen(n);
if(m==1)n1=n[0]-'0';
else
 {
 strcpy(n,n+m-2);
 n1=(n[0]-'0')*10+n[1]-'0';
 }
s=0;
for(i=1;i<=n1;i++)
 {p=i%10;
  q=i%4;
  if(q==0)q=3;
  else q--;
  s=(s+r[q][p])%10;
  }
g<<s<<'\n';
}
f.close();
g.close();
return 0;
}