Hello - as Lanny stated, iPads do not have spinning HDs but use flash memory (specifically NAND) like SSDs and USB memory sticks - these flash memory modules are small - as an example, the pics below are several from a 'teardown' of a 64 GB iPad Pro (LINK) - the first shows the main electronic chips/storage/etc - the second a zoomed in look w/ the 64 GB Toshiba NAND flash memory unit. So unless you want to do this 'difficult' teardown and remove the storage unit, then you might have to put in a BUNCH of random holes -
Also, consider recycling the iPad once you erase the contents as suggested - a couple of months ago, I had a 1 TB spinning HD crash (was for Time Machine BUs) - reformatted w/ higher security settings and then drilled a large hole through the drive - in a box now w/ other electronic recyclables - will drop off at Best Buy in the near future. Dave
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