Every subway rider’s worst fears were reignited over the weekend when a 61-year-old man on his way to brunch with his wife was fatally shoved in front of an oncoming train by a complete stranger. The act was random, rare, and completely unprompted — which is precisely why it’s so terrifying. But just how likely is it that you’ll get pushed onto the subway tracks by a complete stranger? Let’s find out.

To figure out the odds, I emailed David Spiegelhalter, a math professor and one of the authors of The Norm Chronicles: Stories and Numbers About Danger and Death. He told me that the easiest way to estimate something like this is to use the following formula: “Number of events per year [over] Total exposure to risk per year.”

According to the New York Times, this weekend’s death was the first time since late 2012 that a subway rider was purposefully pushed in front of a train by another. This means there have been two events in the last two years — one from 2012–2013, and one from 2013–2014 — so we can estimate that’s about one event per year. Meanwhile, the MTA says that there are approximately 1.71 billion subway rides per year.

So what’s the chance of you getting pushed onto the tracks by a complete stranger every time you take the subway? 1 in 1.71 billion.

Of course, this number changes based on how frequently you ride the train. The more subway trips you take, the more your chance of encountering such an event increases. If you ride the subway to and from work every day, that’s approximately 500 trips per year. If you divide the total number of rides per year — 1.71 billion — by 500, you get 3.42 million. So, every year you have a 1 in 3.42 million chance of getting shoved by a stranger.

“That’s around the average daily risk of an accidental or violent death in the U.S. So the subway compares favorably with driving, et cetera,” explains professor Spiegelhalter. “But the psychological difference is the fear factor of the random maniac. Numbers don’t tell the whole story.”

Happy commuting!