
BINARY NUMBERS
The system of numbers in everyday use is the denary or decimal
system of numbers, using the digits 0 to 9. It has ten different
digits $(0, 1, 2, 3, 4, 5, 6, 7, 8$ and $9)$ and is said to have a radix or
base of $10$.
The binary system of numbers has a radix of 2 and uses only
the digits $0$ and $1$.
Conversion of Binary to Denary
The denary number $234.5$ is equivalent to
$2\times{10^2}+3\times{10^1}+4\times{10^0}+5\times{10^{-1}}$
i.e. is the sum of terms comprising: (a digit) multiplied by (the
base raised to some power).
In the binary system of numbers, the base is $2$, so $1101.1$ is
equivalent to: $1\times 2^3 + 1\times 2^2 + 0 \times 2^1 + 1\times 2^0 + 1\times 2^{−1}$
Thus the denary number equivalent to the binary number
$1101.1$ is
$8+4+0+1+\frac{1}{2}$, that is $13.5$.
i.e. $1101.12=13.5_{10}$, the suffixes $2$ and $10$ denoting binary and
denary systems of numbers respectively.
Example 1: Convert $11011_2$ to a denary number.
$11011_2=1\times 2^4+1\times 2^3+0\times 2^2+1\times 2^1+1\times 2^0$
$=16+8+0+2+1$
$=27_{10}$
Example 2: Convert $0.1011_2$ to a decimal fraction
$0.1011_2=1\times 2^{-1}+0\times 2^{-2}+1\times 2^{-3}+1\times 2^{-4}$
$=1\times\frac{1}{2}\times 0\times\frac{1}{2^2}+\frac{1}{2^3}+1\times\frac{1}{2^4}$
$=\frac{1}{2}+\frac{1}{8}+\frac{1}{16}$
$=0.5+0.125+0.0625$
$=0.6875_{10}$