https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&feedformat=atom&user=Danielparksexplain xkcd - User contributions [en]2026-04-14T17:16:18ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=3213:_Dental_Formulas&diff=4073623213: Dental Formulas2026-02-27T22:04:41Z<p>Danielparks: Fix typo in transcript ("mammologists" in comic)</p>
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<div>{{comic<br />
| number = 3213<br />
| date = February 27, 2026<br />
| title = Dental Formulas<br />
| image = dental_formulas_2x.png<br />
| imagesize = 212x337px<br />
| noexpand = true<br />
| titletext = I mean, half of these are undefined. And your multiplication dots are too low; they look like decimal points.<br />
}}<br />
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==Explanation==<br />
{{incomplete|This page was created recently. Don't remove this notice too soon.}}<br />
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A {{w|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.<br />
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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.<br />
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'Mammologists' is also misused; the correct term is Mamm''a''logists. Mammologists study human breasts specifically, usually in a medical context.<br />
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==Transcript==<br />
{{incomplete transcript|Don't remove this notice too soon.}}<br />
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:[Cueball and Megan are standing in front of a whiteboard, on which is written<br />
::<u>3.1.3.1</u><br>3.1.2.1<br />
:along with some other scribbles.<br />
:Underneath the panel is the caption, "Mathematicians encounter dental formulas".]<br />
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Cueball: Do mammologists think these are hard?<br />
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Cueball: I mean this one just evaluates to 3/2.<br />
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{{comic discussion}}<noinclude></div>Danielparks