## Teaser 2824: New extension

**From The Sunday Times, 6th November 2016** [link]

George has just moved departments and he has a new four-figure telephone extension number. He shows it to Martha and proudly points out that, if you delete any two of the digits of the extension number, then the remaining two-figure number is prime. Martha then lists the resulting six different primes and comments delightedly that more than one of them divides exactly into the extension number.

What is George’s new extension number?

[teaser2824]

## Jim Randell 9:55 am

on21 August 2019 Permalink |We can express the puzzle as a set of alphametic constraints and use the [[

`SubstitutedExpression()`

]] solver from theenigma.pylibrary to solve it.The following run file executes in 81ms.

Run:[ @repl.it ]Solution:George’s new extension number is 4371.4371 is divisible by 47 and by 31.

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## GeoffR 8:43 am

on22 August 2019 Permalink |LikeLike