Part 4: Lucky Numbers Summary and Analysis

Feynman develops a knack for using logic to solve arithmetic problems in his head, a skill he largely credits to the influence of Hans Bethe, a scientist he works with at Los Alamos.

In Brazil, he encounters a Japanese man in a restaurant who prides himself on his ability to make calculations with an abacus very quickly. Feynman greatly distresses the man when he is able to outperform him without even using an abacus—he does all of the math in his head. He tries to explain the logic tricks he uses to the Japanese man with the abacus but is unsuccessful. The man has a very limited concept of the math involved, and is merely highly skilled at operating the abacus.