There is a simple technique to convert English numbers to Nepali numbers in WordPress via a custom function.

The Custom function to be inserted in function PHP file is:

//for converting eng number into nepali number
function EnToNp($string) {
        $array = array("0" => "०","1" => "१","2" => "२","3" => "३","4" => "४","5" => "५","6" => "६","7" => "७","8" => "८","9" => "९"); 
        return strtr($string,$array);
 }

Now to use the function we can simply use the function as:

<?php echo EnToNp("9");?>

As per the above example, as a result of the method EnToNp, the number is converted to Nepali format. This is how we can simply achieve the result.