Miku

10的任何次方mod9都是1

所以说事实上就是把l到r加起来而已

然后等差数列求和即可

2在mod9意义下的逆元是5

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
using namespace std;
int mod=9;
long long Simex,Ariche;
int n;
int main(){
    scanf("%d",&n);
    for(int i=1;i<=n;++i){
        scanf("%lld%lld",&Simex,&Ariche);
        cout<<(Simex%mod+Ariche%mod)*((Ariche-Simex+1)%mod)%mod*5%mod<<endl; 
    }
    return 0;
}