The other day, when I was making my little jokes about 20/20 vision and losing my glasses (in a very 2020 way), I found myself pondering things about the number 20. And that pondering led to some enumerating, and that enumerating became a list. On this 20th day of the month, and in the tradition of my ThThTh lists (but breaking tradition since it’s not Thursday), I present a list of things around the theme of 20. And it seemed only right to have a list of 20 of them.
1) 20/20 vision: Normal vision. It is based on what row of an eye chart you can read from 20 feet.
2) The 20-20-20 rule. To help with eyestrain. For every 20 minutes you find yourself staring at a screen, spend 20 seconds looking at something that is 20 feet away.
3) 20/20 hindsight. An expression meaning that things are clear in retrospect, typically after some misjudgment.
4) venti: size at Starbucks. It’s 20 ounces, and it means twenty in Italian. It’s sort of the “large” size, though there is also grande (which means “large” in Italian), but is smaller than the venti.
5) icosagon or 20-gon is a twenty-sided polygon
6) icosahedron: a polyhedron with 20 sides. The shape of a 20-sided die.
7) Twenty questions: a guessing game whereby one person thinks of a thing, and the second person tries to guess what it is by way of asking yes-no questions. The guesser wins if they name the correct thing before reaching the twentieth questions. (Experienced players know that it’s a good idea to narrow down the categories early on, rather than guessing one item in the universe of millions of things, i.e: Is it pants? This is the game for which “Is it bigger than a breadbox” and “is it smaller than a house” are frequent size-establishing questions.)
8) Vigesimal: base 20 number system
9) a score: a term meaning the number twenty. Fairly infrequent, excepting in quotations of the Gettysburg Address. (“Four score and seven years ago…”)
10) XX: The Roman numeral for 20
11) 20th anniversary gift: china/porcelain
12) a dart board has 20 sections
13) The (current) US twenty dollar bill. A frequent denomination distributed in ATMs in the U.S. Currently bears the face of Andrew Jackson.
14) Harriet Tubman 20 dollar bill. 2020 was supposed to be the year when abolitionist and historical bad-ass Harriet Tubman was supposed to replace Jackson on the 20 dollar bill. This has been put off, but many have taken the transformation into their own hands and used a stamp. (See image above.)
15) 20 is the smallest primitive abundant number.
16) 20 is the atomic number of calcium.
17) 20/20: a new-oriented US TV program.18) Twenty (2015): a South Korea film.
19) Twenty (2017-2018) a webseries.
20) The Roaring 20s. A nickname for the decade of 1920 to 1929. Now that we are in another decade of the 20s, we can only guess what it will be nicknamed.
It appears that I am quite partial to the number 11. Not the least because I regularly post at 
The number 11 has featured prominently in quite a few posts over the years, in particular on 11/11. In anticipation of the exciting (at least to me) date of 11/11/11, I 
collecting tokens 