SEATTLE, WA — President Donald Trump has said several times this week that public school teachers should be armed to defend against school shootings. At first, Trump suggested just arming teachers who have had gun training, like retired military personnel. But on Thursday, he said maybe 20 percent of all teachers should be armed.

Public schools are notoriously cash-strapped. Washington has been under-funding public schools in violation of the state Constitution for years, according to the McCleary decision. Now, many state residents will see a big property tax increase to pay for billions in new school funding (not to mention local levies still in effect). Here's the hard math: There are about 54,000 public school teachers in Washington, according to the Superintendent of Public Instruction. Twenty percent of that is 10,800.

A Glock 17 handgun, which is the gun many police officers carry, costs about $600. Cost to arm 20 percent of the state's teachers: $6.4 million.

But there's more. A gun needs to be loaded with ammunition. A box of 9mm bullets costs about $15, but varies from store to store. Each armed teacher would also need a concealed pistol license. That costs $48, according to the state Department of Licensing. Paying for ammo and licenses adds another $680,400 — so now we're up to $7.08 million.

But don't forget training. The Firearms Academy of Seattle charges $95 for an introductory course on handgun use. But tuition for the defensive training class — including shooting at moving targets, accuracy, how to draw a gun - costs $425. You can't take the defensive class without taking the basic class. Cost for 10,800 teachers: $5.6 million.

To keep up that training, teachers will have to go to the gun range. At Champion Arms in Kent, the range fee is $13.50. Going to the range every other month, plus maybe three boxes of ammo per pop, that's another $631,800.

Now the total cost is up to $13.2 million. One last cost: Trump has suggest that armed teachers should get "a little bit of a bonus" in pay for bearing such a heavy burden. What's a little bit? Last month Walmart promised to give some employees a one-time $1,000 bonus - so let's use that number.