A_3 B_2 is a sparingly soluble salt of molar mass M ( g mol^-1) and solubility x g L^-1. The solubility product satisfies K_sp =a(x/M)^5. The value…

$\displaystyle \mathrm{A}_3 \mathrm{~B}_2$ is a sparingly soluble salt of molar mass $\displaystyle \mathrm{M}\left(\mathrm{g} \mathrm{mol}^{-1}\right)$ and solubility $\displaystyle x \mathrm{~g} \mathrm{~L}^{-1}$. The solubility product satisfies $\displaystyle \mathrm{K}_{\mathrm{sp}}=a\left(\frac{x}{\mathrm{M}}\right)^5$. The value of $\displaystyle a$ is \_\_\_\_. (Integer answer)