I have five cards bearing the figures 1, 3, 5, 7, and 9. How can I arrange them in a row so that the number formed by the first pair multiplied by the number formed by the last pair, with the central number subtracted, will produce a number composed of repetitions of one figure?
Thus, in the example I have shown, 31 multiplied by 79 and 5 subtracted will produce 2444, which would have been all right if that 2 had happened to be another 4.
Of course, there must be two solutions, for the pairs are clearly interchangeable.
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