#include <stdio.h>
#include <ctype.h>

int main()
{
    int i,t,sum,k,nr;
    char c1,c2,c3;
    freopen("cifra.in","r",stdin);
    freopen("cifra.out","w",stdout);
    scanf("%d",&t);
    getchar();
    for(i=1; i<=t; i++){
        c1=getchar();
        c2=getchar();
        if(isdigit(c2)){
            c3=getchar();
            while(isdigit(c3)){
                c1=c2;
                c2=c3;
                c3=getchar();
            }
        }
        c1-='0';
        c2-='0';
        if(!isdigit(c2+'0')) nr=c1;
        else nr=c1*10+c2;
        sum=0;
        for(k=1; k<=nr; k++)
        {
            if(k%10==1) sum++;
            if(k%10==2)
                if(k%4==1) sum+=2;
                else
                    if(k%4==2) sum+=4;
                    else
                        if(k%4==3) sum+=8;
                        else
                            sum+=6;
            if(k%10==3)
                if(k%4==1) sum+=3;
                else
                    if(k%4==2) sum+=9;
                    else
                        if(k%4==3) sum+=7;
                        else
                            sum+=1;
            if(k%10==4)
                if(k%2==1) sum+=4;
                else
                    sum+=6;
            if(k%10==5) sum+=5;
            if(k%10==6) sum+=6;
            if(k%10==7)
                if(k%4==1) sum+=7;
                else
                    if(k%4==2) sum+=9;
                    else
                        if(k%4==3) sum+=3;
                        else
                            sum+=1;
            if(k%10==8)
                if(k%4==1) sum+=8;
                else
                    if(k%4==2) sum+=4;
                    else
                        if(k%4==3) sum+=2;
                        else
                            sum+=6;
            if(k%10==9)
                if(k%2==1) sum+=9;
                else
                    sum++;
        }
        printf("%d\n",sum%10);
    }

    return 0;
}