Thread: deriving numbers

I want to derive numbers from the characters mentioned below
characters : crvcrcrx
where c = 8 then what would be the rest of the numbers
hint available to me is that the derived number is of 8 digits i.e., each character represents a number

I got a further clue. There's a series in the number for example 85985857 i.e 59 58 57 is the series.