1~7AC 8~10WA

#include<bits/stdc++.h>
using namespace std;
unsigned long long l,r,q,ans;
int main(){
	cin>>q;
	while(q--){
		cin>>l>>r;
		ans=(l+r)*(r-l+1)/2;
		cout<<ans-ans/9*9<<'\n';
	}
	return 0;
}