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Comment by TheAceOfHearts | Hacker News Reader

Another example of confusing numeric systems emerges from 12-hour clocks. For many people, asking them to specify which one is 12AM and which one is 12PM is likely to cause confusion. This confusion is immediately cleared up if you just adopt a 24-hour clock. This is a hill I'm willing to die on.

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A few months ago, my girlfriend and I missed a comedy show because we showed up on the wrong day. The ticket said Saturday 12:15am, which apparently meant Sunday 12:15am, as part of the Saturday lineup. Still feel stupid about that one.

That sounds like their error. If the ticket said Saturday 2am, you wouldn't show up at Sunday 2am, right?

You usually know it from context, and if not, 12 noon or 12 midnight is quite common.

But I do wished people would stop writing schedules in the 12 hour system. You get weird stuff like bold means PM etc. to compensate for the space inefficiency of 12 hour system

> just adopt a 24-hour clock. This is a hill I'm willing to die on.

I don't know if I feel that strongly about it but I tend to agree. I see more value in adopting a 24 hour clock than making SI mandatory. AM/PM is silly.

That's not inherent to AM/PM, it's cause for some reason the AM/PM switches on the boundary of 11 to 12, not 12 to 1. To fix this while still having AM work with 24hr time, it should be 0 instead of 12

Yeah it's just weird that a new day starts at 12am, and that the jump from am to pm happens from 11 to 12. If we made the day start at 0am, the noon start at 0pm, things are just logical. If you take x am to be x hours since the new-day marker, (or x pm to be x hours since noon), then you'd naively expect 12am to be noon. You could argue that we work modulo 12, but the extra am/pm bit means that it's not fully the same as working in Z/12Z.

That’s why I always say “12 noon” when writing out scheduling instructions for something at 12PM.

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