 In 1940 he became the winner of the sixth Moscow secondary school mathematical olympiad.In August 1942, after completing his first year at Moscow State University's Faculty of Mechanics and Mathematics, Yablonsky, then 17, went to serve in the Soviet Army, fighting in the second world war as a member of the tank brigade 242.For his service he was awarded two Orders of the Patriotic War, two Orders of the Red Star, Order of Glory of the 3rd class, and numerous medals.