3213: Dental Formulas
| Dental Formulas |
 Title text: I mean, half of these are undefined. And your multiplication dots are too low; they look like decimal points. |
Explanation
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A dental formula specifies the number of teeth of each type on each side of the jaw, with dots separating the numbers. There are two rows, representing the upper and lower jaw, separated by a horizontal line. The number of incisors is indicated first, canines second, premolars third, and finally molars, so the formula in the comic would represent 3 incisors, 1 canine, 3 premolars, and 1 molar on each side of the upper jaw, and equal numbers in the lower jaw except only 2 premolars. The adult human dental formula is 2.1.2.3 for both the upper and lower jaws.
Cueball is (wrongly) treating a dental formula as an arithmetic expression, with the line indicating division and the dots indicating multiplication. In the title text he notices that "half the formulae are undefined" representing animals that lack one of the four types of teeth listed above. He also notes that the "dots are too low", as in fact the dots in a dental formula are at the height of period characters and aren't meant to imply multiplication.
'Mammologists' is also misused; the correct term is Mammalogists. Mammologists study human breasts specifically, usually in a medical context.
Transcript
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This is one of 46 incomplete transcripts: Don't remove this notice too soon. If you can fix this issue, edit the page! |
- [Cueball and Megan are standing in front of a whiteboard, on which is written
- 3.1.3.1
3.1.2.1
- 3.1.3.1
- along with some other scribbles.
- Underneath the panel is the caption, "Mathematicians encounter dental formulas".]
Cueball: Do mammologists think these are hard?
Cueball: I mean this one just evaluates to 3/2.
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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)
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