The molar concentrations $(M$, i.e. $m o l / L)$ of some ionic species in a water sample were estimated as follows:
$\mathrm{Na}^{+}=0.25{\mathrm{M} ; \mathrm{Ca}^{2+}}^{2}=0.12 \mathrm{M} ; \mathrm{Cl}^{-}=0.32 \mathrm{M} ; \mathrm{HCO}_{3}^{-}=0.05 \mathrm{M}$.
The ionic strength of this water sample is __________$\mathrm{M}$ $\text{(correct up to two decimal places)}$.
