dig = {1:1, 3:7, 7:3, 9:9}
 
def solve(n, x):
    y = dig[x % 10]
 
    for i in range(1, n):       # to add (n-1) zeroes in prod
        for j in range(10):     # checks whether j * 10^i + y is ok or not
 
            temp = pow(10, i) * j + y
            prod = str(x * temp)[::-1]      # [::-1] -> string in reverse order
 
            if i < len(prod) and prod[i] == '0':
                y = temp
                continue
 
    return y if x*y % 10**n == 1 else '0'
 
for _ in range(int(input())):
    n, x = map(int, input().split())
 
    print(solve(n, x))

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NQoxIDkKMSA3CjIgMTEKMyAxNwo1IDExMzI3

5
1 9
1 7
2 11
3 17
5 11327