In the few days the app has been available to download, Pokémon Go has already launched a global phenomenon. The goal, of course, is to catch them all, but the game has had a few unintended consequences as well. It’s helped players find dates, get some accidental exercise, and now, Gizmodo reports, it’s teaching Americans the metric system.

At least 7.5 million of the users who’ve downloaded the app so far are in the U.S., a country where it's generally not necessary to know how long it takes to walk one kilometer. Pokémon Go is changing that. Instead of measuring distance in miles, the game follows the metric system—just like the majority of the world.

Walking is a big part of the game; to find new Pokémon, players need to go to new places until they appear. One component even forces players to walk a certain distance to accomplish the goal. To hatch a common Pokémon egg, users must walk two kilometers, and to hatch a rare one, they need to walk five kilometers. A lot of players in the U.S. apparently have no concept of how far that is: According to Google Trends, searches for the phrases “how far is 2 km” and “how far is 5 km” spiked after July 6.

If you haven’t gotten around to Googling it yet, there’s .62 miles in a kilometer, making two kilometers equivalent to 1.2 miles and five kilometers to 3.1 miles. There’s no way to switch units from metric in the app, so Pokémon Go players may want to commit those numbers to memory.

[h/t Gizmodo]

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