One-Letter Quiz

The answer to each question below is a letter of the alphabet. Each letter is used exactly once. (Thanks for the idea, Ask Me Another.) Good luck!

Want to amuse your friends, irritate your students, or annoy people you’ve just met? Download a PDF version of the One-Letter Quiz (without answers).

1. The letter used to represent the square root of -1.
2. This letter is often added to indefinite integrals to show that any function with at least one antiderivative has an infinite number of them.
3. The most frequently occurring letter in English words.
4. The letter most recently added to the modern, 26-letter English alphabet.
5. The letter represented by four dots in Morse Code.
6. A type of road intersection with three arms.
7. Although long out of use, this letter was used in the middle ages as the Roman numeral to represent 90.
8. This letter is used for the temperature scale in which the boiling point is 212 degrees and the freezing point is 32 degrees.
9. The most common blood type.
10. The rating from the Motion Picture Association of America that requires children under 17 to be accompanied by an adult.
11. The 43rd President of the United States.
12. The only vowel that does not appear in the spelling of any single-, double-, or triple-digit numbers.
13. Behind s and c, the third most common letter with which English words begin.
14. With plan, the letter used to refer to a typically less desirable alternative.
15. The Roman numeral for 500.
16. The symbol for potassium on the periodic table.
17. The most common variable in algebra.
18. The Roman numeral for 5.
19. The “score” used to indicate the number of standard deviations a data point is from the mean.
20. The letter commonly used to refer to the vertical axis on a coordinate graph.
21. Although every adult can recognize the loop-tail version of this lowercase letter in print, less than one-third of participants in a Johns Hopkins study could correctly pick it out of a four-option lineup.
22. The clothing size that increases when preceded by an X.
23. The shape of the “happiness curve,” which implies that most people are least happy in their 50’s.
24. The shape of a logistic growth curve, which increases gradually at first, more rapidly in the middle, and slowly at the end, leveling off at a maximum value after some period of time.
25. The only letter that does not appear in the name of any US state.
26. The answer to the riddle, “It occurs once in a minute, twice in a moment, but never in a thousand years.”

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Answers (and Notes of Interest)

1. I
2. C
3. E
4. J : in 1524, Gian Giorgio Trissino made a clear distinction between the sounds for i and j, which were previously the same letter
5. H
6. T
7. N : see Wikipedia for a list of other Roman numerals used in medieval times
8. F
9. O
10. R
11. W : should probably be “Dubya” instead of “Double U,” but whatever
12. A
13. P : as you might expect, more English words start with S than any other letter; based on the ENABLE word list, P is the second most common initial letter, followed by C
14. B
15. D
16. K : the symbol K comes from kalium, the Medieval Latin for potash, from which the name potassium was derived
17. X
18. V
19. Z
20. Y
21. G : a lowercase g can be written in two different ways, and the more common version in typesetting (known as the “loop-tail g“) can be recognized but not written by most adults, as recounted on the D-Brief blog
22. L
23. U : see this article from The Economist, especially this image
24. S
25. Q
26. M