He never said school shootings, just school children getting shot (a term which refers to young kids)
"In 2019, before the coronavirus pandemic, there were 1,732 gun deaths among U.S. children and teens under the age of 18. By 2021, that figure had increased to 2,590."
https://www.pewresearch.org/short-r...s-among-us-kids-rose-50-percent-in-two-years/
Most kids who die from gunshots aren't from school shootings - and this is just deaths
Probably not crazy to assume the number of total shot is more than the ~2600 or so that die from being shot
And presumably he is talking about USA? USA has about 1050 billionaires
So to give a conservative estimate let's say 3000 US kids shot per year, 1000 billionaires
You're right, the math is off - it would take 4 months, so it was off by a factor of 2
Edit:
NVM, non fatal shootings is about 11,000
"there were more than 11,000 emergency-room visits for gunshot injuries among children and teens under the age of 18"
So if just going by shot it's a little over 1 month, for shot and killed it's a little over 4 months