Q: how do i download the free apps without them asking me billing address

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Create an iTunes App Store account without a credit card

App Store Frequently Asked Questions (FAQ)

If you have already created an apple I'd, then the only way is to add a credit card and then remove it after your I'd has been verified or use a iTunes gift card.

This is apple's way of verifying not only your identity but your age as well. Certainly not full proof,and probably could use some tweaking, but that's how it is for now.