#include <cstdio>
#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <cmath>
#include <string>
#include <cstring>
#include <sstream>
#include <algorithm>
using namespace std;

typedef long long ll;
typedef pair <int, int> ii;

const int Maxn = 50005;
const int Maxm = 500015;
const int nil =  250005;
const int Maxp = 230;

int has[Maxn];
int my[Maxm];
ll res;
int L[Maxn], R[Maxn];
vector <ii> quer[Maxp];
ll ans[Maxn];

int Get(int x)
{
	int res = 0;
	while (x) {
		if (x % 10 == 4) res--;
		if (x % 10 == 7) res++;
		x /= 10;
	}
	return res;
}

void Add(int val)
{
	res += my[val + nil]++;
}

void Rem(int val)
{
	res -= --my[val + nil];
}

int main()
{
	cin.sync_with_stdio(false);
	for (int i = 1; i < Maxn; i++)
		has[i] = Get(i) + has[i - 1];
	int q; cin >> q;
	for (int i = 0; i < q; i++) {
		int l, r; cin >> l >> r; l--;
		if (r - l + 1 <= Maxp) {
			for (int j = l; j <= r; j++)
				Add(has[j]);
			ans[i] = res;
			for (int j = l; j <= r; j++)
				Rem(has[j]);
		} else {
			quer[l / Maxp + 1].push_back(ii(r, i));
			L[i] = l; R[i] = r;
		}
	}
	for (int i = 0; i < Maxp; i++) if (!quer[i].empty()) {
		int curL = i * Maxp, curR = i * Maxp;
		sort(quer[i].begin(), quer[i].end());
		for (int j = 0; j < quer[i].size(); j++) {
			int ind = quer[i][j].second;
			while (curR <= R[ind]) { Add(has[curR]); curR++; }
			while (curL < L[ind]) { Rem(has[curL]); curL++; }
			while (L[ind] < curL) { curL--; Add(has[curL]); }
			ans[ind] = res;
		}
		while (curL < i * Maxp) { Rem(has[curL]); curL++; }
		while (curR > i * Maxp) { curR--; Rem(has[curR]); }
	}
	for (int i = 0; i < q; i++)
		cout << ans[i] << endl;
	return 0;
}