Tag Archives: Calculus

Mental Arithmetic in Russia

Mental Arithmetic. S.A.Ratxinski’s Public school (1895)

Nikolai P. Bogdanov-Belsky (1868 – 1945) painted this classroom with eleven students resolving the problem written on the blackboard: (102 + 112 + 122 + 132 + 142)/365. Professor  Sergei Ratxinski is in a poor public school because of kids’ clothes and he’s listening… what? What is this little blond boy saying? He has probably discovered that 102 + 112 + 122 = 132 + 142.  In this case, the solution is very simply!

Location: Tretiakov Gallery in Moscow (map)

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