#nullable enable

#region
var (_input, _iter) = (Array.Empty<string>(), 0);
T I<T>() where T : IParsable<T>
{
    while (_iter >= _input.Length) (_input, _iter) = (Console.ReadLine()!.Split(' '), 0);
    return T.Parse(_input[_iter++], null);
}
#endregion

static T[] Range<T>(int n, Func<T> F) => Enumerable.Range(0, n).Select(_ => F()).ToArray();

static (long d, long x, long y) ExtendedGCD(long a, long b)
{
    var (x0, y0, x1, y1) = (1L, 0L, 0L, 1L);
    while (b != 0)
    {
        var q = a / b;
        (a, b) = (b, a - q * b);
        (x0, y0, x1, y1) = (x1, y1, x0 - q * x1, y0 - q * y1);
    }
    return (a, x0, y0);
}

static long? ModDiv(long a, long b, long m)
{
    if (b == 0) throw new DivideByZeroException();
    var (d, t, _) = ExtendedGCD(b, m);
    if (a % d != 0) return null;
    if (d < 0) (d, t) = (-d, -t);
    var dm = m / d;
    var y = (long)((Int128)a / d * t % dm);
    if (y < 0) y += dm;
    return y;
}

long Solve()
{
    var xs = I<string>();
    var x = int.Parse(xs);
    var m = I<int>();
    var k1 = 1L;
    var k2 = 1L;
    var l = xs.Length;
    for (var i = 0; i < l; i++) k1 *= 10;
    for (var i = 0; i < 18 - l; i++) k2 *= 10;
    var r = (k2 + 1) * x;
    var q = -r % m;
    if (q < 0) q += m;
    var yo = ModDiv(q, k1, m);
    if (yo == null) return -1;
    var y = yo.Value;
    return r + y * k1;
}

var t = I<int>();
var ans = Range(t, Solve);
Console.WriteLine(string.Join(Environment.NewLine, ans));