Ho do I install Numbers on Apple iPad 2 OS 9.3.5

To use Apple’s productivity Apps, you will need a device capable of running iOS/iPadOS 13.x or later.

As all iPads capable of running iPadOS13.x also run iPadOS14, this is the definitive list of iPads that are capable of installing and running the currently available version of Apple Numbers:

You don't.

Apple, unlike many third party app developers, never retains older versions of their own apps to encourage users to keep purchasing newer hardware devices that support THE LATEST versions of their apps.

IF you don't have any of Apple's iWork apps on that iPad, now, ( like Pages, Numbers and Keynote ), it is impossible to get these now.

An iPad 2 is an over 10-year old device ( introduced March/April of 2011 ).

It's 2021, now.

Apple ended support for all 8-10-year old iOS devices nearly 5 years, ago, in 2016.

Third party app developers abandoned and stopped supporting these 8-10-year old iOS devices nearly 3 years, ago, in 2018.

There are, virtually, NO MORE third party apps available from the iOS App Store, any longer!

Third party compatible apps for such old devices are few and far between, now, in 2021.

This includes Apple apps and vryally ALL third party apps for both iOS 9 AND iOS 10 devices!

Simply put, a 2nd gen iPad is too old and obsolete now.

Sorry, but this is the reality for ALL 8-10-year old AND OLDER iOS devices now. Especially now in 2021!

If you need/want an iPad with an up to date iPadOS with access to current, updated apps, then you really need to seriously consider a purchase of a new iPad model OR a much, MUCH “newer” and less expensive, refurbished or used iPad models, from better known, trusted Apple product/device retailers/resellers, some locally or from online, on the Web/Internet, capable of running the latest iPadOS versions.

There are PLENTY of less expensive, newer, older iPad models that can run the latest, current versions of iPadOS.

I am sorry that you had to learn all of this, but this does not change any of the facts regarding these very old iOS devices.

Sorry & Best of Luck to You!

You don't, sorry, since Numbers app requires iPadOS 13.1 or later, not suppoerted by your iPad model because of hardware (CPU/RAM) incompatibility.

Regards

Giulio