Last December, we published our 2017 Science and Math Crossword as a holiday gift to Quanta readers. This year, I’m happy to say, it’s back by popular demand.

The 2018 crossword is similar to the 2017 crossword in many ways. Like last year’s, the new crossword is a celebration of the excellent scientific articles that Quanta served up all year, and it’s also my tribute to Quanta’s writers and editors. But I also made some changes this time around.

Features that stayed the same:

1. The crossword grid is identical to the one used in 2017.
2. Many of the clues refer to Quanta articles published in 2018 and mention the writer’s name in parentheses at the end of the clue.
3. As before, most clues conform to the style employed in cryptic crosswords, where every clue is itself a puzzle as described in this Wikipedia entry, which explains how cryptic clues work. They make heavy use of wordplay such as anagramming, double meaning and other tricks that leave no doubt about the correctness of the answer, since they point to it in multiple ways. I offer a few examples below.
4. The number of letters in the target word or phrase is given in parentheses to make your task a little easier. Answers having multiple words are denoted by the number of letters in each word, separated by commas.

New features:

1. Some of this year’s clues are associated with numbers. The numbers are sometimes part of the answer itself: A square may contain a single decimal digit instead of a letter. In this case, the length of the clue is prefixed by the hash (#) symbol. At other times, letters themselves may represent a number in a way that will be obvious. Finally, the clue itself may contain a number. Since all this is a departure from traditional cryptic crosswords, here are some example clues:
   • “Messages that are used to build all other messages? In English, that’s the lot!” (7,#2)
     • Answer: LETTERS26, and the associated number is 26.
   • Decimal-based input/output (2)
     • Answer: IO, and the associated number is 10.
   • A four-letter-word month meets four-numbered day and boom — fireworks!
     • Answer: JULY, and the associated number is 4.
2. In order to help you solve the numerical clues, I have constructed an algebraic formula that relates all of them. This formula is at the bottom of the crossword and is reproduced here:

1D – (47A)(54A) – (1A)(18A – 55A) + 47A – 55A – 55A = 0

To solve this, you will have to substitute the number-letter combinations, such as “47A,” in the above formula with the number associated with the appropriate crossword clue, which, in this case, is 47 Across.

This year, a Quanta T-shirt or one of the two new Quanta books, Alice and Bob Meet the Wall of Fire or The Prime Number Conspiracy (winner’s choice), will be awarded for this puzzle. The prize will go to the best alternative clue for any of the puzzle answers, posted in the comments section below. Please do not include the answer itself in your comments. (Comments containing answers will not be published.) You are welcome to discuss clues in the comments. Let us know which ones you like best!

Happy reading and solving and best wishes to all for the holidays. We will publish the answers in mid-January and be back with a new Insights puzzle in February.

Download the crossword as a PDF to print or as a *.puz file to play in the Across Lite app.

Updated on Jan. 11, 2019: The puzzle solution is now available here in PDF format. The crossword prize winner is Douglas Felix, who contributed several interesting alternative clues. His clue for the word “log” — “the last word from a drowning number theorist” — was especially hilarious. Congratulations!