因为:1 < (1!+2!+3!+4!+5!+...+n!)/n!< (1!+2!+...(n-2)!+(n-1)!+n!)/n!< [(n-2)!(n-2)+(n-1)!+n!]/n! 1/n + 1/n + 1所以:lim(n->∞) (1/n + 1/n + 1 ) = 1 ,由两边夹法则:lim(n->∞) (1!+2!+3!+4!+5!+...+n!)/n!...