#include <bits/stdc++.h>
using namespace std;
long long modulo(long long n) {
if (n < 10) return n;
return modulo(modulo(n / 10) + (n % 10));
}
long long sum(long long l, long long r) {
int sum = 0;
for (int i = l; i <= r; i++) {
sum += modulo(i);
}
return sum;
}
int main() {
long long q;
cin >> q;
vector<pair<long long, long long>> query(q);
for (int i = 0; i < q; i++) {
long long x, y;
cin >> x >> y;
query[i].first = x;
query[i].second = y;
cout << sum(query[i].first, query[i].second) << endl;
}
}
