What would be the Google Sheets formula to search for a matching value in a range that goes across multiple rows an columns? For example I need to search the entire range H:P (all rows and columns) and find the cells with a matching value, if any. Ultimately in this case I need just a list of the row numbers where a matching cell is found. In the screenshot there are two matches highlighted in green. There is a match on O2, and on M3. So in this case I need a result like "2,3".
I have tried various things for several hours with no luck. Most examples of formulas that I could find and understand are about looking up in either a single column, or row.
Any help appreciated! Thank you!