I always resent these puzzles for being deliberately misleading and using “+” and “=” in a devious way. Con artists, some of these puzzle writers.
I keep thinking “YOU’RE LYING!!! That is not a ‘+’ function. Why don’t they just use commas and then challenge readers to find the pattern?”
They don’t gain anything by lying — ie by using symbols with long-established and widely accepted definitions as placeholders for the mystery function which the reader is challenged to discover.
Another early problem for me was that I didn’t want to violate the integrity of numbers and calculate digits separately. When digits abutt their neighbors, it means something. It’s a promise and civilized people will honor that promise.
You can create puzzles (or for that matter art) without this sabotage.
Once I realized the vulgar barbarity of these puzzle writers they became much easier.