What are the maximum number of apps for an iPad?

In theory I would say 4400. You can have eleven home screens and the iPad will hold up to 20 folders on a screen and 20 apps in each folder - AFAIK.

I have no clue if that many will actually install - but I know my math is correct as are the numbers allowed on the iPad with regard to screens, folders and apps.

There is a maximum of 11 screens after which apps won't be visible, they will only be accessible via the iPad's spotlight search screen (swipe the first homescreen to the right). But as you can have up to 20 app folders per screen, each with 20 apps in, you could potentially have over 4000 'visible' apps

You can install as many apps as you can fit in the memory of your device. However, only 4400 of them will appear on the screen (given that you have set it up like Demo suggests). Anything else you'd need to access through a Spotlight search. (I can't state with certainty that you could exceed 4400 on a 64 gig iPad. However, it is quite possible on 16 gig iPhone to exceed the number of apps that can be displayed.)

Best of luck.

Does the iPad 1 turn on Restrictions if you have more that 11 pages of apps? I tried to install another app and it's greyed out. I don't recall setting Restrictions.