Translations:Help:Magic words/202/en

Takes an unformatted number (Arabic, no group separators and  as decimal separator) and outputs it in the localized digit script and formatted with decimal and decimal group separators, according to the wiki's default locale.

The  parameter can be used to reverse the behavior, for use in mathematical situations: it's reliable and should be used only to deformat numbers which are known to be formatted exactly as formatnum formats them with the wiki's locale.