>400 x 400 teachers >160,000 >64,000,000 dead people
That doesn't seem feasibly possible. Roman historians would have probably commented on a massacre so grandiose if it ever happened, because they kept logs and documented on practically everything. Roman population was 1 million at one point, and that was an anomaly since most cities didn't have such a big population in ancient times. And the Roman empire at its peak was still only 60-70 million inhabitants around every providence it had.