Scholomance Meta: Population Statistics

So I read the two Scholomance novels, and have latched on with the joy of someone who has found Dubious Worldbuilding. Specifically, there is no way the family sizes as seen and wizard death rates, ages 0 - 18, add up.

( Let's talk numbers. Spoilers for A Deadly Education and The Last Graduate. )

So yeah, I am dying for book 3, which hopefully will drop more shoes, pull guns of the mantelpiece, etc etc etc.