procedural programming – How to repeat the number of times that a nested loop does an iteration?

I'm trying to write a nested for loop that displays the 00 to 55 pairs, each digit ranging from 0 to 5.

In other words, I want the output to appear as follows: 00, 01, 02, 03, 04, 05, 10, 11, …, 50, 51, 52, 53, 54, 55.

I know I can do it using two variables, one representing the first digit and the other the second. I also know how to create a for loop that prints, for example, numbers from 0 to 5 once, but how can I get Mathematica repeat this process 5 times for the output model to continue up to 55?