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Junior Balkan MO
1998 Junior Balkan MO
1
Prove that 111...11222...225 is a perfect square
Prove that 111...11222...225 is a perfect square
Source: 0
October 30, 2005
induction
Perfect Square
Problem Statement
Prove that the number
111
…
11
⏟
1997
22
…
22
⏟
1998
5
\underbrace{111\ldots 11}_{1997}\underbrace{22\ldots 22}_{1998}5
1997
111
…
11
1998
22
…
22
5
(which has 1997 of 1-s and 1998 of 2-s) is a perfect square.
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