Do the players get to know what number they got hit with?

[Pierson_Lowgal]

The way shield etc... works clearly indicates that GMs tell PCs the attack roll. The podcast and video podcast confirm that Chris Perkins & Dave Noonan tell the PCs the numbers.

 

[KarinsDad]

THE DMG goes into the pros and cons of the DM rolling in the open vs behind a DM screen.

I was surprised that the DMG almost treated this subject objectively.

Previous DMGs (and this one as well) tend to have a lot of terminology which implies "an only or best way to play the game".

This one was a lot more even handed in this case. However, that entire section has a lot of "best ways" and "don'ts" it.