$re = '/^(\d+)(?:\.0+|(\.\d*?)0+)$/m';
$str = '1.7500
1.1010
1.0000
10
1.0000010
1.10
1.0
1.10001000102342
1.10001000102342000000';
$subst = "$1$2";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php