#include <bits/stdc++.h>
using namespace std;
 
#define file(name) if (fopen(name".INP", "r")){freopen(name".INP", "r", stdin); freopen(name".OUT", "w", stdout);}
 
const int maxn = 1e6 + 7;
 
void solution(){
 
	long long a, b;
	cin >> a >> b;
	cout << (long long)b*(b+1)/2 - a*(a-1)/2 << "\n";
 
}
 
signed main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);
 
	file("TEST");
 
	int test = 1; cin >> test;
	while (test --> 0) solution();
 
	return 0;
}
 

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