Consider the following statements regarding 1's and 2's complement representation:

​The 1's complement of a binary number is obtained by simply inverting all its bits, changing every 0 to a 1 and every 1 to a 0.

​The 2's complement of a binary number is calculated mathematically by adding 1 to its 1's complement.

​In an 8-bit 2's complement system, the binary sequence 1111 1111 represents the decimal number -128.

​Which of the statements given above is/are correct?