Prize Bonds Face Value

[Hen]

I have prize bonds from 1957 and ones from the 80s/90s pre Euro. Now the website says You can cash your Prize Bonds in at any time after the minimum holding period of 90 days and you will receive the full face value on your bonds within seven working days.

So what does this mean? How do I calculate the price of my individual prize bonds?

 

[Annie51]

Each bond is €6.25 value.

 

[Cervelo]

As far as I know the bonds from 1957 will be worth €6.35 not €6.25. I'm not sure about the 80/90s bonds would be worth more then €6.25