PHP Taskbook Level 3.6
Given an array of numbers, remove numbers from it that have more than three digits.
Given a number, for example, like this:
$num = 12345;
Check that all digits of this number are greater than zero.
Given some array, for example, like this:
[123, 456, 789]
Merge all the elements of this array into one array, splitting them character by character:
[1, 2, 3, 4, 5, 6, 7, 8, 9]
