**From New Scientist #1676, 5th August 1989** [link]

I’m in the middle of a game of dominoes and I’m looking at the four dominoes laid end-to-end on the table.

If I replace the number of spots by digits and then read off the four-figure number formed by the first two dominoes, I get a perfect square. (For example, had the dominoes been:

then I’d have read the number 1220).

The four-figure number formed by the middle two dominoes (which would be 2005 in the above example) is a prime.

And the total number of spots on the four dominoes is a perfect square.

What are the four dominoes.

[enigma524]

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Suppose the dominoes are:

Then we can solve the puzzle using the [[

`SubstitutedExpression()`

]] solver from theenigma.pylibrary.The following run file executes in 139ms.

Run:[ @repl.it ]Solution:The 4 dominoes are: [2-1] [1-6] [6-3] [3-3].If we allow duplicate dominoes the following are also solutions: