Formatting a Number in PHP

Задание 1

Given a string:

php<?php
  $str = '12345678';
?>

Make it into a string:

php'12 345 678'

Задание 2

Given a number:

php<?php
  $number = 9876543.21;
?>

Format the number so that it has thousands separators (space) and two digits in the fractional part:

php'9 876 543.21'

Задание 3

Given a number:

php<?php
  $price = 1234.5678;
?>

Format the number with thousands separators (dot), two digits in the fractional part, and a currency symbol:

php'€1.234,57'