Did you figure out 7-4's secret in SMB without the internet?

[Marioro]

As a kid I looked it up and that's how I found out what path to take. Years later I realized I just had to pay attention to the sounds when this puzzle appeared in other games.

EDIT: When making the question I assumed y'all first played the level as kids, but maybe some did as adults. Oh well.

 

[Hint Toad]

Do you mean NSMB? If you meant NSMB then yeah, had to use the internet. It was the last thing I needed to do to 100% the game.

Edit: I remember searching for the hidden exit in the under ground vertical level filled with pipes. It seemed like a good level to hide a hidden exit.