"Each digit is 5 bits long, comprising a 4 bit bcd digit and a parity bit"

If you'd have said that in the first place, you'd have saved about eight wasted posts as people tried to guess what on earth you meant by "5-bit bdc [sic]"

I hope you have learned an important lesson here: please be sure to provide the full facts of the case from the outset - it will save everyone (including you) a whole lot of time!