
Here is an extended description
Description
string number_format ( float $number [, int $decimals = 0 ] )
string number_format ( float $number , int $decimals = 0 , string $dec_point = '.' , string $thousands_sep = ',' )
This function accepts either one, two, or four parameters (not three):
If only one parameter is given, number will be formatted without decimals, but with a comma (",") between every group of thousands.
If two parameters are given, number will be formatted with decimals decimals with a dot (".") in front, and a comma (",") between every group of thousands.
If all four parameters are given, number will be formatted with decimals decimals, dec_point instead of a dot (".") before the decimals and thousands_sep instead of a comma (",") between every group of thousands.