Dependency

for (auto i = 0u; i < 90; ++i) {
  sum *= 10;
  sum += a[i];
}

for (auto i = 0u; i < 90; i += 3) {
  sum *= 1000;
  sum += a[i] * 100;
  sum += a[i + 1] * 10;
  sum += a[i + 2];
}

* The benchmark is run under Apple Macbook Air M2.

* For the full benchmark code, please refer here.