Raidho

 
ملحق شده: 2016-07-14
I never saw a wild thing sorry for itself...
امتیاز36بقیه
مرحله بعد: 
Points needed: 164

Mental calculation

Nikolay Petrovich Bogdanov-Belsky. Mental calculation. In the public school of S.A. Rachinsky (1895).

231011962

No calculators. No paper. No pens. Only own wits.
A rural Russian school. The late XIXth century.
Is it too much for you?