Pro tip: Super Mario Bros. 3's coin ships

Play Super Mario Bros. 3 enough and you'll eventually come across ships loaded with coins. They take the place of Hammer Bros. on some of the overworld maps. But where do they come from? What triggers them? Good news for you, it's not random.

Let's take a look at the typical end of stage area.

Looks pretty normal, right? But there are five things to take note of here

Item 1: You have to be at the end of the stage, and get a card. The card you get doesn't matter
Item 2: You have to be in World 1, 3, 5, or 6. You can't do this in World 7 because there aren't any Hammer Bros. there
Item 3: Your tens digit of your score, note this
Item 4: Your coin count has to be a multiple of 11, but can't be zeros, and the digits have to match the tens digit of your score
Item 5: Your time when you get the card has to be an even number. Okay, that's not strictly true, but without going into details that involve math, just make it even

Once you have all these criteria met, the next time you go to the map screen one of the Hammer Bros. (if there are any left) will turn into a ship loaded with coins.