php how to display zeros after dot?

Question

PHP

How can I specify a template for a number and cast it to this form?
for example 2 dots after the comma:
12.23
12.20
12.00
i.e. the number of decimal places is unchanged

Answer 1

number_format($number, 2, '.',' ');

Answer 2

printf("%01.2f", 100.1);