#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

const int MAX_N = 50100;

int countDigit(int nr, int d) {
  int ans = 0;
  while(nr) {
    ans += (nr % 10 == d);
    nr /= 10;
  }
  return ans;
}

int fors[MAX_N];
int sevens[MAX_N];

int counter[MAX_N];
long long ans;

const int SQRT_VAL = 224;

struct query {
  int l, r, poz;
  query(int _l = 0, int _r = 0, int _poz = 0) {
    l = _l;
    r = _r;
    poz = _poz;
  }

  inline bool operator < (const query &other) const {
    if(l / SQRT_VAL == other.r / SQRT_VAL) {
      return r > other.r;
    }
    return l / SQRT_VAL < other.l / SQRT_VAL;
  }
};

vector<query> queries;

long long sol[MAX_N];

int main()
{
  cin.sync_with_stdio(false);

  for(int i = 1; i < MAX_N; i++) {
    fors[i] = fors[i - 1] + countDigit(i, 4);
    sevens[i] = sevens[i - 1] + countDigit(i, 7);
  }

  int n;
  cin >> n;
  for(int i = 1; i <= n; i++) {
    int a, b;
    cin >> a >> b;
    queries.push_back(query(a, b, i));
  }
  sort(queries.begin(), queries.end());

  int lastX = queries[0].l;
  int lastY = queries[0].r;

  counter[0] = 1;
  for(int i = lastX; i <= lastY; i++) {
    ans += counter[fors[i] - sevens[i]];
    counter[fors[i] - sevens[i]]++;
  }

  sol[queries[0].poz] = ans;

  for(auto it = queries.begin() + 1; it < queries.end(); it++) {
    if(it->l >= lastX) {
      for(int i = lastX; i < it->l; i++) {
        counter[fors[i] - sevens[i]]--;
        ans -= counter[fors[i] - sevens[i]];
      }
    }
    else {
      for(int i = it->l; i < lastX; i++) {
        ans += counter[fors[i] - sevens[i]];
        counter[fors[i] - sevens[i]]++;
      }
    }

    if(lastY <= it->r) {
      for(int i = lastY + 1; i <= it->r; i++) {
        ans += counter[fors[i] - sevens[i]];
        counter[fors[i] - sevens[i]]++;
      }
    }
    else {
      for(int i = it->r + 1; i <= lastY; i++) {
        counter[fors[i] - sevens[i]]--;
        ans -= counter[fors[i] - sevens[i]];
      }
    }

    lastX = it->l;
    lastY = it->r;
    sol[it->poz] = ans;
  }

  for(int i = 1; i <= n; i++) {
    cout << sol[i] << '\n';
  }

  return 0;
}