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ASU 244 All Soviet Union MO 1977 2 perfect squares create a fine number

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July 6, 2019
Perfect Squarenumber theory

Problem Statement

Let us call "fine" the 2n2n-digit number if it is exact square itself and the two numbers represented by its first nn digits (first digit may not be zero) and last nn digits (first digit may be zero, but it may not be zero itself) are exact squares also.
a) Find all two- and four-digit fine numbers.
b) Is there any six-digit fine number?
c) Prove that there exists 2020-digit fine number.
d) Prove that there exist at least ten 100100-digit fine numbers.
e) Prove that there exists 3030-digit fine number.