Solubility of calcium phosphate (molecular mass= M) in water is W_g per 100 mL at 25°C. Its solubility product at 25°C will be

$C{a}_3{\left(P{O}_4\right)}_2\rightleftharpoons 3C{a}^{+2}+2P{O}_4^{3-}$
Solubility product $={\left(3s\right)}^3{\left(2s\right)}^2=108S^5$
Given solubility = Wg per 100 ml
S = 10 W per 1 $\Rightarrow \frac{10W}{M}moles/L$
$K_{SP}={10}^5\times 108\times \frac{W^5}{M^5}$