The 16-bit 2's complement representation of an integer is 1111 1111 1111 0101; its decimal representation is _________ .

The given 16-bit binary number is:

Since the most significant bit (MSB) is $1$, the number is negative in 2's complement representation.

To find its decimal value:

1. Find the 1's complement of the number:

   $$0000\ 0000\ 0000\ 1010_2$$

2. Add $1$ to find the magnitude (2's complement of the negative number):

   $$0000\ 0000\ 0000\ 1010_2 + 1 = 0000\ 0000\ 0000\ 1011_2 = 11_{10}$$

3. Apply the negative sign:

   $$\text{Decimal value} = -11$$

Alternatively, calculate the weighted sum directly: