How BigInteger convert a byte array to number in Java?

I have this small code :

public static void main(String[] args)  {

    byte[] bytesArray = {7,34};
    BigInteger bytesTointeger= new BigInteger(bytesArray);
    System.out.println(bytesTointeger);

}

Output:1826

My question is what just happened how an array of bytes {7,34} converted into this number 1826 , what is the operation that caused this result ? like how to convert it manually