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 Digit addition and insertion (Posted on 2011-10-27)
(I) Determine all possible base ten 8-digit perfect square(s) N, with no leading zeroes, such that the number obtained by increasing the second digit (reading left to right) of N by 1 is also a perfect square.

(II)Determine all possible base ten 4-digit perfect square(s) N, with no leading zeroes, such that the number obtained by inserting two zeroes between the thousands digit and the hundreds digit of N is also a perfect square.

**** Calculators are allowed, but no computer programs.

 No Solution Yet Submitted by K Sengupta Rating: 5.0000 (1 votes)

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 re: answers Comment 2 of 2 |

Must be just a typo, but 7569 = 87^2, not 86^2.

Some variations, found via forbidden tree of knowledge:

If wrap-around of digits is allowed so that 9 is incremented to 0, then

29702500 =  5450^2 and 20702500  = 4550^2

If, however, when you do this you also carry the 1 from what's actually a 10, you get:

99500625 = 9975^2 and   100500625 = 10025^2

 Posted by Charlie on 2011-10-27 18:31:11

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