I work for a school district in the tech dept. We have around 300 Acer R721T chromebooks. I have worked on several of them with numbers keys that are not working, usually 1,2,3 and 4. Sometimes I am able to fix the problem by reseating the keyboard ribbon cable, resetting the chromebook or formatting it. Unfortunately if any of those fixes work it is only temporary. I am wondering if they keyboards are defective? I am seeing this more on the first fleet we purchased which were out of warranty in 11/21.
[Edited the content to add model number to the title]