Styrene $($A$)$ and butadiene $($B$)$ are to be polymerized in series of CSTRs each of volume $26\mathrm{.}5m^3$ according to the $2^{nd}$ order reaction:

$A+BP,r_A={10}^{-5}{C}_A{C}_B$

If the initial concentration of styrene is $0\mathrm{.}795mo\frac{l}{l}it,$ of butadiene is $3\mathrm{.}55mo\frac{l}{?}$ lit and

${}_{\text{m}\text{i}\text{x}}=870k\frac{g}{m^3}$

with a feed rate of $19\mathrm{.}7$ ton$/$h:

What is the total number of reactors required for polymerization of $30\%$ of the limiting reactant?