由 訪客 於 星期三 八月 03, 2005 12:25 pm
[n/5]+[n/25]+[n/125]+[n/625]+[n/3125]+[n/15625]
[15625/5]+[15625/25]+[15625/125]+[15625/625]+[15625/3125]+[15625/15625]
=3125+625+125+25+5+1=3906
即15625 < n < 78125
(n/5)+(n/25)+(n/125)+(n/625)+(n/3125)+(n/15625)≧5437
0.249984n≧5437
n≧21749
[21749/5]+[21749/25]+[21749/125]+[21749/625]+[21749/3125]+[21749/15625]
=4349+869+173+34+6+1
=5432
[21750/5]+[21750/25]+[21750/125]+[21750/625]+[21750/3125]+[21750/15625]
=4350+870+174+34+6+1
=5435
[21760/5]+[21760/25]+[21760/125]+[21760/625]+[21760/3125]+[21760/15625]
=4352+870+174+34+6+1
=5437
[21764/5]+[21764/25]+[21764/125]+[21764/625]+[21764/3125]+[21764/15625]
=4352+870+174+34+6+1
=5437
[21765/5]+[21765/25]+[21765/125]+[21765/625]+[21765/3125]+[21765/15625]
=4353+870+174+34+6+1
=5438
n=21760,21761,21762,21763,21764