1. Is this a positive or a negative number?
1100 0101 1110 1011 is the binary representation of a negative integer, on 16 bits (2 Bytes).
In a signed binary, the first bit (the leftmost) is reserved for the sign,
1 = negative, 0 = positive. This bit does not count when calculating the absolute value.
2. Construct the unsigned binary number.
Exclude the first bit (the leftmost), that is reserved for the sign:
1100 0101 1110 1011 = 100 0101 1110 1011
3. Map the unsigned binary number's digits versus the corresponding powers of 2 that their place value represent:
214
1 213
0 212
0 211
0 210
1 29
0 28
1 27
1 26
1 25
1 24
0 23
1 22
0 21
1 20
1
4. Multiply each bit by its corresponding power of 2 and add all the terms up.
100 0101 1110 1011(2) =
(1 × 214 + 0 × 213 + 0 × 212 + 0 × 211 + 1 × 210 + 0 × 29 + 1 × 28 + 1 × 27 + 1 × 26 + 1 × 25 + 0 × 24 + 1 × 23 + 0 × 22 + 1 × 21 + 1 × 20)(10) =
(16 384 + 0 + 0 + 0 + 1 024 + 0 + 256 + 128 + 64 + 32 + 0 + 8 + 0 + 2 + 1)(10) =
(16 384 + 1 024 + 256 + 128 + 64 + 32 + 8 + 2 + 1)(10) =
17 899(10)
5. If needed, adjust the sign of the integer number by the first digit (leftmost) of the signed binary:
1100 0101 1110 1011(2) = -17 899(10)
The number 1100 0101 1110 1011(2) converted from a signed binary (base two) and written as an integer in decimal system (base ten):
1100 0101 1110 1011(2) = -17 899(10)
Spaces were used to group digits: for binary, by 4, for decimal, by 3.