Talk:3213: Dental Formulas

First!AmethystSky14 (talk) 21:43, 27 February 2026 (UTC)

The top left drawing is a tooth. Xkdvd (talk) 22:04, 27 February 2026 (UTC)

This confused me for a long time (partly due to the mammal/mammol thing) - I took them to be dentists. I'm now inferring that the counts are typical of a species rather than descriptive of an individual patient. Maybe the write up could make that more clear in case someone else as dumb as me passes by 2A00:23EE:10C8:110F:D992:D45:1C7A:DF02 guest

"in case someone as dumb as me passes by" - that would be everyone, see Explain xkcd: It's 'cause you're dumb. 64.201.132.210 22:21, 27 February 2026 (UTC)

Yes, dental formulas are based on typical, not individual, dentition. In cases where it frequently varies (like humans with their unreliable wisdom teeth) you sometimes see a range. 70.40.90.209 02:29, 28 February 2026 (UTC)

Because I'm sure someone else will be wondering, based on a very cursory search, the formula on the board appears to be permanent teeth for felines. At the very least, Wikipedia's entry on Dentition lists this formula for cats, lions, and tigers. Perhaps an actual expert will come along and shed further light on this. 97.116.61.145 22:52, 27 February 2026 (UTC)

Some British sources still use a baseline dot (full stop/period) as the multiplication symbol and a midline dot (interpunct) as the decimal point. These sources could write 3.2·1 = 6·3. Scary. Even The Lancet uses the interpunct as a decimal point (though its style guides do not specify a multiplication symbol, so presumably '×' should be used when juxtaposition isn't an option, e.g. for scientific notation). Most British schools still teach it this way as well, where the dot product is always a baseline dot. (This convention also used in some other European countries, which use the comma as the decimal separator and the period as the thousands separator. But it's confusing, because 〈x,y〉or even (x,y) is also used to represent the inner product of x and y. It's really a mess.) EebstertheGreat (talk) 04:36, 28 February 2026 (UTC)

I didn't know it was called the interpunct but that was how I was taught to write decimal points at my UK school in the early sixties and how I still write them by hand.--2A00:23CC:D248:8901:30F4:4052:A4F7:386E 09:36, 28 February 2026 (UTC)

And some countries use interpuncts for multiplying scalars, baseline dots (interchangeably with spaces, but never both in a single number) for thousands, and commas as decimal symbol. There are languages that even include group separation after the latter, with a 4-digit final group iff the last digit is the 10^-3n-1s place (e. g. "3 863 387,274 479 0001" instead of "3 863 387,274 479 000 1"), even with several exceptions (e. g. rules like "4-digit numbers do not require formatting, unless they are in a table with longer numbers in the same column"). 2001:4C4E:1C00:EB00:D063:D715:3937:44C6 11:42, 1 March 2026 (UTC)

I was taught, in the UK in the '80s, to use the '×' symbol. It seems that practically everybody else uses some sort of dot, or worse just stuffs the variables side by side and the multiplication is "assumed". Hmm, and some people wonder why maths causes so much distress. 2A01:CB08:82C3:1A00:F550:3C0C:BC34:851E 19:29, 6 March 2026 (UTC)

I probably significantly overlap you, in locale and timeframe, so here's my take on that: When learning basic arithmatic (primary school level) I'd be using the notation × (and ÷, to go along with + and -), but by the time it came to algebra (in secondary level education) then dotted adjacency was preferable (as well as using a ")(" writing style for the variable "x", to be extra-sure it's not mistaken as a multiplication). So you have the likes of "y = mx + c" or "y=ax² + bx + c". And, by this point, the difference between cross product and dot product potentially become very important... Technically, the '1d vectors' that are plain numbers are multiplied in dot-product fashion to create the requisite scalar (i.e. also 1d) that you'd expect through all prior experiences of multiplication. And this continues into higher and further education levels.

If using the cross, at this level, it risks the impression that you are using the cross-product. If obeying its calculative rules, creates a result that is perpendicular (and anti-commutative, so dependent upon order applied) to the vectors supplied. Trying to apply a cross-product to single-values essentially tells you that they have zero angular difference between the two two (whether in the same of opposite directions) and no magnitude in the co-perpendicular direction (requiring 3d of vector-space, or more). (And I hope I explained that right, and am not using my own understanding of the terminology in a way that doesn't match more standard uses of it. ;) ) 81.179.199.253 21:26, 6 March 2026 (UTC)

An unrelated note, I'm just curious, does any beast have more than 1 canine? or is the second number limited to the set {0, 1}? -- Malgond (talk) 09:31, 2 March 2026 (UTC)

Fun Fact: The São Tomé collared fruit bat is the only known mammal where the whole population has an asymmetrical dental formula. --134.102.219.31 18:51, 2 March 2026 (UTC)

Although "mammals in general" have breasts not all do. The platypus is a mammal and does produce milk to feed its young, however it has no nipples. Instead an area of skin "leaks" (secretes) milk into the fur. Martin (talk) 21:01, 2 March 2026 (UTC)

A platypus? Commercialegg (talk) 01:32, 3 March 2026 (UTC)

With a fedora? 93.176.188.2 16:50, 4 March 2026 (UTC)