User blog comment:Kallutofan990/Why does Killua's age say his 14 currently?/@comment-4783583-20131107150759

the hunter exam takes place only once a year, so we know at least a year passed when they were in greed island and killua left to take the new hunter exam. With all that has happened during the chimera ant and the hutner elections arcs one could speculate that took another year,