Numbers
The number 8 in braille
8 is the number sign followed by the letter h — dots 1, 2 and 5.
Number sign + h
Dots 3-4-5-6, then dots 1-2-5
Why it uses a letter
The first ten letters of the alphabet double as the ten digits. h is letter 8 of the alphabet, so after a number sign it reads as 8. Without the number sign the same cell is simply the letter h — see H in braille.
8 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.
8
18
800