In the decimal system we would write a number like $9.90625$ in what is called the normalized scientific notation. $$9.90625=0.990625\times 10^{1},$$ and a real non-zero number could be generalized as $$\begin{equation} x=\pm r\times 10^{{\mbox{n}}}, \tag{1} \end{equation}$$ with $r$ a number in the range $1/10 \le r < 1$. In a similar way we can use represent a binary number in scientific notation as $$\begin{equation} x=\pm q\times 2^{{\mbox{m}}}, \tag{2} \end{equation}$$ with $q$ a number in the range $1/2 \le q < 1$. This means that the mantissa of a binary number would be represented by the general formula $$\begin{equation} (0.a_{-1}a_{-2}\dots a_{-n})_2=a_{-1}\times 2^{-1} +a_{-2}\times 2^{-2}+\dots+a_{-n}\times 2^{-n}. \tag{3} \end{equation}$$