By the time he reached 14 years of age he was already attending research seminars in mathematics in Kiev. However, Krein never completed his undergraduate degree for he left his home in Kiev when he was 17 years old and ran away to Odessa.
Ng oras siya umabot ng 14 taong gulang siya ay dumadalo sa research seminar sa matematika sa Kiev. Gayunman, Krein hindi natapos ang kanyang undergraduate degree siya sa kaliwa para sa kanyang tahanan sa Kiev kapag siya ay 17 years old at tumakbo palayo sa Odessa.