Our original prize crossnumber is featured on pages 64 and 65 of Issue 23.
- Download Crossnumber #23 as a PDF, or read on!
- Submit your answer
Rules
- The digits 0 to 9 (inclusive) each appear exactly once in every row and column of the completed crossnumber.
- There is only one solution to the completed crossnumber. Solvers may wish to use the OEIS, Python, Microsoft Encarta, etc to (for example) obtain a list of prime numbers, but no programming should be necessary to solve the puzzle. As usual, no entries begin with 0.
- One randomly selected correct answer will win a £100 Maths Gear goody bag, including non-transitive dice, a Festival of the Spoken Nerd DVD, and much, much more. Three randomly selected runners up will win a Chalkdust T-shirt. Maths Gear is a website that sells nerdy things worldwide, with free UK shipping.
- To enter, submit the sum of all the digits in the row marked by arrows using this form by 18 August 2026. Only one entry per person will be accepted. Winners will be notified by email and announced in issue 24.
Crossnumber
Crossnumber #23, set by Humbug:
More from Chalkdust
Read Issue 23 now!
Sleep, coffee and cheating at Tetris feature in our SS26 issue! Plus all your favourite puzzles & columns.
Dear Dirichlet, Issue 23
Travel, trade and Tony Blackburn pepper the prof's postbag this issue
Comic: Introduction to catalysis
If you'll open your textbook to page... oh, the cat's sitting on it
What’s hot and what’s not, Issue 23
Fashion is fleeting, Chalkdust regulars are not.
The big argument: 6 or 7?
✋ Which is best? 🤚
Which generation are you?
Always banging on about how numbers were better in the good old days? Take our quiz to find out how old you really are…