Share price is 431.10 how much are they worth if I own 817 shares
If the share price was 5c and you owned 10 of them. What would they be worth?
Hopefully you can see that the answer would be 5*10 = 50c
Your question is the same only the numbers are more scary.
so you must do it the same way.
When you have scary numbers always swap them to easy numbers to see what you would do.