Conversion of fractional part of a hexadecimal number to binary
Here is how to convert the fractional part from hexadecimal to binary:
$$
(0.25)_{16} = \frac{2}{16} + \frac{5}{16^2} =
\frac{0 \cdot 8 + 0 \cdot 4 + 1 \cdot 2 + 0 \cdot 1}{16} +
\frac{0 \cdot 8 + 1 \cdot 4 + 0 \cdot 2 + 1 \cdot 1}{16^2} = \\
\frac{0}{2} + \frac{0}{4} + \frac{1}{8} + \frac{0}{16} + \frac{0}{32} + \frac{1}{64} + \frac{0}{128} + \frac{1}{256} = (0.00100101)_2
$$
As you can see, we simply replace $2$ with its base 2 representation, and then adjoin the base 2 representation of $5$. I included this calculation to show why this works.
Note also that $(0.25)_{16} \neq 1/4$.