Problem of the Week

This summer I attended a show featuring a self-proclaimed "mentalist". As proof of his mind reading skills he performed the following act:

He asked a woman in the audience to choose a five digit positive integer, then reverse the order of its digits and subtract the smaller from the larger of the two. Then after asking her for the last three digits of this difference, he correctly told her the first two digits by "reading her mind."

Explain how you, too, could perform this amazing feat.

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