You could use a RE, which may not be the best approach. But here it is anyway, and it seems to work great. :)

use strict;
use warnings;

while ( <DATA> ) {
    chomp;
    print "$_ => ";
    s/(?<=\.)(.+?)0+$/$1/;
    print "$_\n";
}

__DATA__
1.25000000
4.60
8.0990010000
25
[download]

Much ado about nothing though, strings can be numified just by using them as numbers.