阶乘结尾多少个零

题目:

100*99*98...*1,结果中有多少个零.

 

 

#!/usr/bin/perl

use strict;

my $n=$ARGV[0];
my $num=0;
for ( 1..$n ) {
        my $tmp=$_;
        while ( $tmp%5==0 ) {
                $num++;
                $tmp/=5;
        }
}
print $num;