## Teaser 2958: Sudoku crossword

**From The Sunday Times, 2nd June 2019** [link]

George and Martha are doing a mathematical crossword. There is a 3×3 grid with the numbers 1 to 9 inclusive appearing once each. The clues are as follows:

Across:top line: a prime number

middle line: a prime number

bottom line: a prime number

Down:left column: a perfect square

middle column: a perfect square

right column: a prime numberAlthough you do not need to know this, one of the diagonal three-digit numbers is also prime.

What is the sum of the three “across” numbers?

[teaser2958]

## Jim Randell 8:18 pm

on31 May 2019 Permalink |We can solve this using the [[

`SubstitutedExpression()`

]] solver from theenigma.pylibrary.This run file executes in 180ms.

Run:[ @repl.it ]Solution:The sum of the three across numbers is 1449.The grid is:

The across numbers are: 283 (prime), 547 (prime), 619 (prime), and their sum is 1449.

The down numbers are: 256 (square), 841 (square), 379 (prime), and their sum is 1476.

The diagonals can be read (left to right) as 249 and 643, and the second of these is prime.

There are no further solutions if the digit 0 is not excluded.

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## GeoffR 8:43 am

on21 June 2019 Permalink |LikeLike