description: Theofanis really likes sequences of positive integers, thus his teacher (Yeltsa Kcir) gave him a problem about a sequence that consists of only special numbers.
  
  Let's call a positive number special if it can be written as a sum of different non-negative powers of n. For example, for n = 4 number 17 is special, because it can be written as 4^0 + 4^2 = 1 + 16 = 17, but 9 is not.
  
  Theofanis asks you to help him find the k-th special number if they are sorted in increasing order. Since this number may be too large, output it modulo 10^9+7.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases.
  
  The first and only line of each test case contains two integers n and k (2 ≤ n ≤ 10^9; 1 ≤ k ≤ 10^9).
  
  Output
  
  For each test case, print one integer — the k-th special number in increasing order modulo 10^9+7.
  
  Example
  
  Input
  
  
  3
  3 4
  2 12
  105 564
  
  
  Output
  
  
  9
  12
  3595374
  
  Note
  
  For n = 3 the sequence is [1,3,4,9...]
solution: import sys
  import math
  from collections import Counter
  input = sys.stdin.readline
  N = int(1e9 + 7)
  #use input().strip() 
  
  
  for _ in range(int(input().strip())):
  	n, k = [int(j) for j in input().strip().split()]
  	b = [0 for i in range(50)]
  	count = 0
  	t = 1
  	a = []
  	while(k):
  		if (k % 2 == 0):
  			k //= 2
  			count += 1
  		elif (k % 2 == 1):
  			k -= 1
  			b[count] += 1
  			if (b[count] > 1):
  				t = 0
  		else:
  			print(-1)
  			t = 0
  		if t != 0:
  			for i in range(50):
  				if (b[i] > 0):
  					a.append(i)
  	a = list(set(a))
  	ans = 0
  	for i in a:
  		ans += pow(n, i, N)
  	print(ans % N)