program cifra;
var a,b,i,s:integer;
    f,g:text;
    y,z:char;
    yy,zz:byte;

function gasire(b:integer):byte;
var n,aux,c:integer;
    ok:boolean;
begin
ok:=true;
case b mod 10 of
     0: begin gasire:=0;ok:=false;end;
     1: begin gasire:=1;ok:=false;end;
     5: begin gasire:=5;ok:=false;end;
     6: begin gasire:=6;ok:=false;end;
end;
if ok then begin
   aux:=b;
   for i:=1 to b-1 do begin
       b:=b*aux;
       b:=b mod 10;
   end;
   gasire:=b;
   {c:=0;
   aux:=b;
   repeat
         INC(C);
         b:=b*aux;
         b:=b mod 10;
         v[c]:=b;
   until aux=(c-1);
   gasire:=b;}
end;
end;


function ultima(b:integer):byte;
var j:integer;
begin
s:=0;
for j:=1 to b do
    s:=s+gasire(j);
s:=s mod 10;
ultima:=s;
end;

begin
     assign(f,'cifra.in');reset(f);
     assign(g,'cifra.out');rewrite(g);
     readln(f,a);
     i:=1;
     while i<=a do begin
         while not eoln(f) do begin
               read(f,y);
               read(f,z);
         end;
         if z=#26 then
            b:=ord(y)-48
         else begin
         yy:=ord(y)-48;
         zz:=ord(z)-48;
         b:=yy*10+zz;
         end;
         readln(f);
         s:=ultima(b);
         writeln(g,s);
         inc(i);
     end;
     close(f);close(g);
end.