#include <bits/stdc++.h>
using namespace std;
struct debugger {
  template <typename T>
  debugger &operator,(const T &v) {
    cerr << v << " ";
    return *this;
  }
} dbg;
inline long long gcd(long long a, long long b) {
  a = ((a) < 0 ? -(a) : (a));
  b = ((b) < 0 ? -(b) : (b));
  while (b) {
    a = a % b;
    swap(a, b);
  }
  return a;
}
long long ext_gcd(long long A, long long B, long long *X, long long *Y) {
  long long x2, y2, x1, y1, x, y, r2, r1, q, r;
  x2 = 1;
  y2 = 0;
  x1 = 0;
  y1 = 1;
  for (r2 = A, r1 = B; r1 != 0;
       r2 = r1, r1 = r, x2 = x1, y2 = y1, x1 = x, y1 = y) {
    q = r2 / r1;
    r = r2 % r1;
    x = x2 - (q * x1);
    y = y2 - (q * y1);
  }
  *X = x2;
  *Y = y2;
  return r2;
}
inline long long modInv(long long a, long long m) {
  long long x, y;
  ext_gcd(a, m, &x, &y);
  x %= m;
  if (x < 0) x += m;
  return x;
}
inline long long bigmod(long long a, long long p, long long m) {
  long long res = 1 % m, x = a % m;
  while (p) {
    if (p & 1) res = (res * x) % m;
    x = (x * x) % m;
    p >>= 1;
  }
  return res;
}
const long long inf = 2147383647;
const long long mod = 1000000007;
const double pi = 2 * acos(0.0);
const double eps = 1e-11;
int N, K;
string low, upp, target;
char tmp[1005];
long long DP[1005][1005][2][2];
int vis[1005][1005][2][2];
int tc = 0;
long long call(int pos, int prv, int sm, int f) {
  if (pos == 0) {
    return f;
  }
  if (vis[pos][prv][sm][f] == tc) return DP[pos][prv][sm][f];
  if (sm == 1) {
    if (vis[pos][prv][sm][f] != 0) return DP[pos][prv][sm][f];
  }
  vis[pos][prv][sm][f] = tc;
  int st = 0, ed = 9;
  if (sm == 0) {
    ed = (target[N - pos] - '0');
  }
  long long res = 0;
  for (long long d = (st); d <= (ed); ++d) {
    int sm2 = sm;
    if (d < ed) sm2 = 1;
    int prv2 = prv;
    int f2 = f;
    if (d == 4 || d == 7) {
      if (prv != 0) {
        int dif = prv - pos;
        if (dif <= K) f2 = 1;
      }
      prv2 = pos;
    }
    res += call(pos - 1, prv2, sm2, f2);
    res %= mod;
  }
  return DP[pos][prv][sm][f] = res;
}
bool islucky(string s) {
  int prv = -1;
  for (long long i = (0); i <= (((long long)(s).size()) - 1); ++i) {
    int d = (s[i] - '0');
    if (d == 4 || d == 7) {
      if (prv == -1) {
        prv = i;
      } else {
        int dif = i - prv;
        if (dif <= K) return true;
        prv = i;
      }
    }
  }
  return false;
}
long long findres(string &s) {
  target = s;
  N = ((long long)(target).size());
  tc++;
  long long res = call(N, 0, 0, 0);
  return res;
}
long long solve() {
  long long res = findres(upp) - findres(low);
  if (res < 0) res += mod;
  res += islucky(low);
  res %= mod;
  return res;
}
int main() {
  int t;
  scanf("%d %d", &t, &K);
  for (long long cs = (1); cs <= (t); ++cs) {
    scanf("%s", tmp);
    low = tmp;
    scanf("%s", tmp);
    upp = tmp;
    long long res = solve();
    printf("%lld\n", res);
  }
  return 0;
}
