Have you ever wondered why airport runways have numbers, and what they might mean? There’s nothing random about these numerals, it turns out. As Atlas Obscura explains in the new video above, each runway number tells you something about its position on the earth—namely, its degree from magnetic north. For the details on how this works, and help on how to decode the numbers yourself, click on the video above.

[h/t Atlas Obscura]

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