php, add trailing zeros if the number is integer

Use the number_format function. If you don't want comma separators, set all four parameters of the function like so (the thousands separator is the fourth parameter):

$number = number_format(1234, 2, '.', '');

Yup, using https://www.php.net/manual/en/function.number-format.php function like this:

$a = 123;
$answer = number_format($a,"2");
echo $answer;

Use sprintf("%0.2f",$a);. docs