Normal division.
2 : 3
2 is bigger than 3, so we know it must be a number less than 1 (0,xxxx)
Now append a zero to 2:
[1] 20 : 3 = (18 + 2) : 3 = 18/3 + 2/3 = 6 + 2/3
So far we have 0,6xxx
But as you can see, wie have the same division (2/3) again. Now repeat [1]...