In base $10$ (i.e. standard numbers), each place value represents a power of $10$. So $0.37$ represents $3$ tenths ($10^{-1}$) and $7$ hundredths ($10^{-2}$). The same principles apply when working in other bases. Hexadecimal is base $16$. So the first place to the right of the decimal represents sixteenths ($16^{-1} = \frac{1}{16}$). Rewriting in base $10$, we get $\dfrac{3}{4} = \dfrac{12}{16}$ . This tells us that in hex, we need $0.C$ since $12_{10} = C_{16}$ (subscripts indicate what base we are working in).