How to build regex for find command with OR
 

I would like to run one find command and find all files with .pdf or .doc file. I can get it to return them individually but I can't do it in one command. Can someone help me please?

Here is what I have:
Both those commands work but how do I get them into one, and add others (e.g. .txt, .chm, etc)?

add an -o

man find

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