Answer
$4.6\times 10^{32}photons/s$
Work Step by Step
We can find the required number of photons per second as follows:
$\frac{n}{t}=\frac{P}{hf}$
We plug in the known values to obtain:
$\frac{n}{t}=\frac{2.70\times 10^{5}W}{(6.63\times 10^{-34}J.s)(8.80\times 10^5Hz)}$
$\frac{n}{t}=4.6\times 10^{32}photons/s$