system
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human
ELI5:  Why do all radio stations end in an odd decimal?

I've noticed all the frequencies in my city end with .1, .3, .5, etc.  I don't know if it's just Vancouver, but can someone please enlighten me as to why?
gpt
An FM radio signal doesn't actually get transmitted on exactly one frequency. FM means *frequency modulation*. What that means is that the way the station sends the sound is by slightly varying the frequency of its signal.

FM radio frequencies are measured in a unit called *megahertz*.

It can vary the frequency by up to 0.1 megahertz, in either direction (higher or lower). So, a station at 106.1 megahertz is actually using frequencies anywhere from 106.0 megahertz up to 106.2 megahertz.

That means that all the radio stations need to be put at least 0.2 megahertz apart to make sure they don't overlap.

Why odd decimals instead of even ones? Well, that's just because the frequencies that are set aside for FM radio in North America are 88.0 megahertz up to 108.0 megahertz. That makes 88.1 megahertz the lowest station frequency, and then they go up by 0.2 from there.