How do I trigger an action only a random number of times?

I want to trigger an action when the player dies but not every time, only once in a while. let's just say once every 10 times the player dies.

System Compare two values : random(100)<10

This will give you 10% chance.

thanks. what if I want the action to be triggered randomly once between every 5 to 10 times the player dies? I want to show interstitial ads when the player is killed but not every time because that would be annoying.

You need a few variables - deathCounter and lastAD (death number when you last shown the ad).

If deathCounter>(lastAD+5), then you can show an ad with 50% chance

Once the ad is shown, set lastAD to deathCounter.

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Another option - you can save the system time when the last ad was shown. If more than 2-3 minutes have past, you can show the ad again.