#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <bitset>
using namespace std;
using ll = long long;
using ld = long double;

template <typename T>
T gcd(const T a, const T b)
{
    return (b != 0) ? gcd(b, a % b) : a;
}

template <typename T>
vector<T> Moebius(vector<T> f)  // Moebius{f}(Y) = \sum_{X \subseteq Y} (-1)^{|Y\X|} f(X)
{
    for (int i = 0; (1LL << i) < f.size(); i++) {
        for (int j = f.size() - 1; j >= 0; j--) {
            if (j & 1LL << i) {
                f[j] -= f[j ^ 1LL << i];
            }
        }
    }
    return f;
}

int main()
{
    int N;
    cin >> N;
    ll M;
    cin >> M;
    vector<ll> a(N);
    vector<ld> p(N);
    for (int i = 0; i < N; i++) {
        cin >> a[i];
    }
    for (int i = 0; i < N; i++) {
        cin >> p[i];
        p[i] /= 100.0;
    }

    const int maximum = 1 << N;
    vector<ld> ex(maximum, 1.0);
    for (int i = 0; i < maximum; i++) {
        for (int j = 0; j < N; j++) {
            if (i & (1 << j)) {
                ex[i] *= p[j];
            }
        }
    }
    ex[0] = 0;
    for (int i = 1; i < maximum; i++) {
        ll LCM = 1LL;
        for (int j = 0; j < N; j++) {
            if (i & (1 << j)) {
                const ll g = gcd(LCM, a[j]);
                const ll b = a[j] / g;
                if (log2(LCM) + log2(b) < 63) {
                    LCM *= b;
                } else {
                    ex[i] = 0;
                    break;
                }
            }
        }
        ex[i] *= (M / LCM);
    }

    const vector<ld> ans = Moebius(ex);
    cout << fixed << setprecision(30) << abs(ans[maximum - 1]) << endl;
    return 0;
}

