In the original Super Mario Bros. (and its huge number of remakes) you get to slide down a flagpole at the end of each level.

Once you slide down and go into the mini-fort, you might see some fireworks, which give you 500 points each. There might be one, three, six, or zero.

But what triggers it?

Great question!

The amount of fireworks you get is dependent on the last digit of the timer when you hit the flagpole. If the digit it 1, 3, or 6, then that's how many fireworks you get. Anything else nets zero.

I find that the best way to guarantee a 6 is to stand on the top step as far left as you can. Then, when the timer's last digit hits 9, hold B, run and jump onto the flagpole. Then you get the 5,000 points and six fireworks for 3,000 more, which nets you a total of 8,000 points (plus the bonus for whatever's left on the timer).

Not too bad!

Oh, and this tip only works on levels that actually have a flagpole. So it's a no-go in the big castle levels.