Depending on language, use a prebuilt function like `number_format()` (or a number and date formatting library, so as not to spend time building code that has already previously been written to perfection), but route it through a middleware that handles internationalization for number and date strings. By using the middleware, you'll be able to pass-in locale and change the number/date strings globally throughout the entire application, without having to later refactor tightly-coupled code to add i18n support.