Henry Ernest Dudeney/Puzzles and Curious Problems/101 - Finding a Square/Historical Note

== Historical Note on by : $101$ - Finding a Square == apparently commented on this puzzle as follows:
 * This application is original on part.
 * Digital properties are but little known to mathematicians, and we hope that his example may serve to direct attention to the method ... In a certain class of arithmetical problems it is of great assistance.