#include <cmath>
#include <fstream>
using namespace std;

long long calculate_solution(const int n, const int r)
{
    for (long long element = 1; ; ++element)
    {
        long long least_number = element * (element - 1) + 1, limit = element - 1;
        auto found = true;
        for (auto i = 1; i < n; ++i)
        {
            long long current_value = least_number + static_cast<long long>(i) * r;
            const auto size = static_cast<long long>(sqrt(current_value - 1)) + 1;

            if (const auto first = size * (size - 1) + 1; current_value < first)
            {
                if (limit < first - current_value)
                {
                    found = false;
                    break;
                }
                least_number += first - current_value;
                limit -= first - current_value;
                current_value = first;
            }

            if (const auto last = size * size; limit > last - current_value)
            {
                limit = last - current_value;
            }
        }

        if (found)
        {
            return least_number;
        }
    }
    return -1;
}

int main()
{
    ifstream input("progresie.in");
    ofstream output("progresie.out");

    int t;
    input >> t;

    for (auto i = 0; i < t; ++i)
    {
        int n, r;
        input >> n >> r;
        output << calculate_solution(n, r) << "\n";
    }

    return 0;
}