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# "The knowledge needed to solve this problem lies in the regularities governing the sum of squares of certain two-digit numbers, named after a celebrated Russian educator"
- URL: https://theparnassian.com/en/reshit-dannyi-primer-pozvoliaiut-znaniia-o-zakonomernostiakh-slozheniia-kvadratov-nekotorykh-dvukhznachnykh-chisel-nazvannykh-imenem-proslavlennogo-rossiiskogo-pedagoga/
- Published: 2020-06-30T20:29:33.000Z
- Updated: 2026-10-01T05:42:34.000Z
- Author: Alexandr Radayev
- Tags: Art, Science, Education, People

10²+11²+12²= 365  
13²+14²= 365

Those whom the subject has intrigued will find an informative note about this painting, and about Rachinsky himself, on [Artchive](https://artchive.ru/artists/2009~Nikolaj%5FPetrovich%5FBogdanovBel%27skij/works/26148~Ustnyj%5Fschet?ref=theparnassian.com)