Mixed numbers don't exist in some countries. If you use them in written form, some people may not understand them at all.

@ColinTheMathmo what are mixed numbers ? 😅

@Turambar From the emoji I assume that's a joke, but from some people it would be a genuine question. Some people really don't know.

So consider 2⅛ ... or in $$\LaTeX$$ ...

$$2\frac{1}{8}$$

Some people don't know that it's 17/8 ($$\LaTeX$$ : $$\frac{17}{8}$$)

@ColinTheMathmo well it was not a joke, for me 2⅛ is like 2×⅛, I never saw this form of writing (I'm a French math student)
When decomposing fractions in real part/fractional part in elementary school, we wrote it 2 + ⅛

@Turambar In England (and Australia) "Mixed Numbers" are a very real thing -- you learn about them early. If you talk about "Two and a half cakes" then you write "2½ cakes" ... the juxtaposition of numbers is, by convention, taken to mean addition.

Similarly, you you write "vingt trois" in digits you write "23", and that doesn't mean "2 times 3".

We have conventions, and the purpose of the original toot is to point out that conventions vary across countries.

In England, 8¾ has the value 8.75.

At school in England in the early 70s I remember being taught decimal notation for numbers as if it were a new and unusual alternative to ordinary fractions.

One had LP records which ran at 33⅓ rpm.

And of course in the 80s one used floppy disks which were 5¼ inches in size. (Well, mini-floppies, strictly, as a floppy was 8 inches.)

(The later 3.5 inch floppy was always 3.5 and never 3½)

Ah, and cassette tape runs at 1⅞ ips!

I wonder if Napoleon converted France?

@EdS Here's a talk about how there are places where people don't know about mixed numbers: