Hecho matemático: 688 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Trivia: 688 is an uninteresting number.
Fecha histórica: November 18th is the day in 1930 that Soka Kyoiku Gakkai, a Buddhist association later renamed Soka Gakkai, is founded by Japanese educators Tsunesaburo Makiguchi and Josei Toda.