#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;
typedef long long int64;
const int kMaxQ = 5e4+10;
const int kSq = 100;

struct Query {
	int l, r, i;
}q[kMaxQ];

int calc(int x) {
	int s = 0;
	while (x) {
		int dig = x % 10;
		if (dig == 4)
			s += 1;
		if (dig == 7)
			s -= 1;
		x /= 10;
	}
	return s;
}

int mark[500010], pre[kMaxQ], finAns[kMaxQ];
int64 ans;

int ind(int x) {
	return x + 250000;
}

void precalc() {
	int maxn = 5e4;
	for (int i = 1; i <= maxn; ++i) {
		pre[i] = pre[i-1] + calc(i);
	}
}

void add(int x) {
	ans += mark[ind(pre[x])];
	mark[ind(pre[x])]++;
	// cout << "Add " << pre[x] << " " << ans << "\n";
}

void rem(int x) {
	mark[ind(pre[x])]--;
	ans -= mark[ind(pre[x])];
	// cout << "Rem " << pre[x] << " " << ans << "\n";
}

int main() {
	precalc();
	int Q;
	cin.sync_with_stdio(false);
	cin >> Q;

	for (int i = 1; i <= Q; ++i) {
		cin >> q[i].l >> q[i].r;
		q[i].i = i;
	}

	auto cmp = [](const Query& a, const Query& b) {
		if (a.l / kSq == b.l / kSq) {
			return a.r < b.r;
		}
		return a.l / kSq < b.l / kSq;
	};

	sort(q+1, q+Q+1, cmp);

	int l = 1, r = 0;
	mark[ind(0)]++;

	for (int i = 1; i <= Q; ++i) {
		while (r < q[i].r) {
			++r;
			add(r);
		}
		while (q[i].l < l) {
			--l;
			add(l-1);
		}
		// cout << l << " " << r << "\n";
		while (r > q[i].r) {
			rem(r);
			--r;
		}
		while (q[i].l > l) {
			rem(l-1);
			++l;
		}

		finAns[q[i].i] = ans;
	}

	for (int i = 1; i <= Q; ++i) {
		cout << finAns[i] << "\n";
	}
}