// Check for the next power of two boundary, to save us a CLZ operation.
    int nextPowerOfTwo = 1 << (bits - 1);

    // Iteratively multiply the longs as big as they can go.
    for (long num = startingNumber; num <= n; num++) {
      // Check to see if the floor(log2(num)) + 1 has changed.
      if ((num & nextPowerOfTwo) != 0) {
        nextPowerOfTwo <<= 1;
        bits++;
      }
      // Get rid of the 2s in num.