After all, a rough assessment suggests that’s what it would cost to secure our K-12 public schools and secondary education facilities. That $10.7 billion number represents two armed security guards being assigned to every public education institution in the nation.

I calculate $10.7 billion based on government statistics which estimate the total number of K-12 public schools at around 99,000 and post-secondary education facilities at around 8,000. That gives 107,000 total. Multiply 107,000 by 100,000 (two security guards each making $50,000 a year) and you get $10.7 billion. I believe $50,000 is a good total estimate for the average security guard salary when taking into account state-level variations in average wage.