#include <bits/stdc++.h>
using namespace std;
using cat = long long;
inline cat get_min_sum_value(cat id, cat K) {
  return K * (K + 1) / 2 + id * (1 + K * K) - (id % K);
}
inline cat get_max_sum_value(cat id, cat K) {
  return K * (K + 1) / 2 + id * (1 + K * K) - (id % K) + K;
}
cat get_sum(cat id, cat K) {
  if (id % K == 0) return id * (1 + K * K) + K * (K + 1) / 2;
  cat small_sum_id = id / K;
  cat min_summand = (id / K) * (1 + K * K) + K + 1 + (id % K - 1) * K;
  while (get_max_sum_value(small_sum_id, K) <= min_summand) {
    min_summand++;
    small_sum_id++;
  }
  if (get_min_sum_value(small_sum_id, K) >= min_summand + K)
    return K * (K - 1) / 2 + K * min_summand;
  if (cat small_sum = get_sum(small_sum_id, K); small_sum <= min_summand)
    return K * (K - 1) / 2 + K * min_summand + K;
  else if (small_sum <= min_summand + K - 1)
    return K * (K - 1) / 2 + K * min_summand + K - (small_sum - min_summand);
  else
    return K * (K - 1) / 2 + K * min_summand;
}
pair<cat, cat> get_first_ge_sum(cat N, cat K) {
  if (N < K * (K + 1) / 2) return {0, K * (K + 1) / 2};
  cat dif = K * (1 + K * K);
  cat cur_id = (N - K * (K + 1) / 2) / dif * K;
  if (get_min_sum_value(cur_id, K) >= N)
    return {cur_id + 1, get_min_sum_value(cur_id, K)};
  cat max_dif = K + K * K;
  cur_id +=
      min(K - 1, (N - get_min_sum_value(cur_id, K) + max_dif - 1) / max_dif);
  if (cat cur_sum = get_sum(cur_id, K); cur_sum < N)
    return {cur_id + 2, cur_sum};
  else
    return {cur_id + 1, cur_sum};
}
cat solve(cat N, cat K) {
  if (N < K * (K + 1) / 2) return N + (N - 1) / K;
  auto [id, sum] = get_first_ge_sum(N, K);
  if (id == -1) return -1;
  if (sum == N)
    return id * (K + 1);
  else
    return (N - id) / K + N - id + 1;
}
int main() {
  cin.sync_with_stdio(0);
  cin.tie(0);
  int T;
  cin >> T;
  while (T--) {
    cat N, K;
    cin >> N >> K;
    cat ans = solve(N, K);
    if (ans == -1) return 1;
    cout << ans << "\n";
  }
}
