Numbers
The number 0 in braille
0 is the number sign followed by the letter j — dots 2, 4 and 5.
Number sign + j
Dots 3-4-5-6, then dots 2-4-5
Why it uses a letter
Zero is the one digit that breaks the obvious pattern. The digits run a=1 through i=9, which uses up the first nine letters, so zero takes the tenth letter, j. It is the commonest slip when learning numbers: reading the j-cell as 10 rather than 0.
0 inside larger numbers
A number sign covers the whole run of digits that follows it, so these examples each use one indicator regardless of length.
0
10
000