+209 A two digit, positive integer,b, is formed by reversing the digits of another two digit, positive integer, a. If both a+b and a-b are perfect squares, what is the value of a?
+33661 Let a = 10n + m and b = 10m + n
Then a - b = 9(n - m)
and a + b = 11(n + m)
These are perfect squares if n - m = 1 and n + m = 11
i.e. n = 6 and m = 5
This makes a = 65 and b = 56
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