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Reversing the square

I have selected a 5-digit number, which is a perfect square. I have created another number by reversing the digits of my perfect square. Neither number has a leading zero. If I subtract the smaller of my numbers from the larger the answer is another perfect square.

Which 5-digit perfect square did I initially select?

WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 18 January. The Editor’s decision is final. Please send entries to Enigma 1675, Â鶹´«Ã½, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address).

Answer to 1669 Coloured bricks: Brick 3 is the hidden brick

The winner David Tomkins of Walsall, West Midlands, UK