MathDB
infinitely many pairs of squares with 2 properties

Source: 1993 German Federal - Bundeswettbewerb Mathematik - BWM - Round 1 p3

November 20, 2022
number theoryPerfect SquaresPerfect Square

Problem Statement

There are pairs of square numbers with the following two properties: (1) Their decimal representations have the same number of digits, with the first digit starting is different from 00 . (2) If one appends the second to the decimal representation of the first, the decimal representation results another square number. Example: 1616 and 8181; 1681=4121681 = 41^2. Prove that there are infinitely many pairs of squares with these properties.