I was looking on the [Wikipedia page](https://en.m.wikipedia.org/wiki/SI_base_unit) for all of the base SI units, and was surprised to see that mole was considered a base unit.
Why is this even a unit? Shouldn’t it be a unit-less quantity? A mole isn’t length, or time, or mass, it’s just a number. Why does it need a unit if it just represents “6×10²³ of something”?
You don’t need units to say “I have 15 pencils,” so why is the mole necessary? It seems like a mole is just a scalar.
In: 10
I guess you could say that, where a gram is a unit if weight and a meter is a unit of length, a mole is a unit of quantity. [A kilogram of steel weighs the same as a kilogram of feathers,](https://youtu.be/-fC2oke5MFg) a meter of road is the same length as a meter of rope, and a mole of hydrogen atoms contains the same number of things as a [mole of moles.](https://what-if.xkcd.com/4/)
Edit: and I would argue that, in your example, “pencil” *is* a unit. Not an SI unit, but a unit. Without it, 15 is just a number. 15 what? 15 joules? 15 lumens? No, 15 pencils.
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