Well, actually that's a bit high, considering kids under 5 or 6 wouldn't technically be in school, and then there's Juvie (another topic altogether)...
So, just taking under 18 and dividing by 18, then multiplying by 13 (K-12), we get 5,417.
Thank you. I didn’t know. It just didn’t seem like a city with a majority concentration to me.