After a long long time, and with a lot of help I've amended some of Fasecero's C library import code for Uint64's - and added some useful functions from my Stringmap library.
This include file gives us a good working start point for Uint64 variables.
If you study the include file you will be able to see the commands and what they do, pretty straight forward really.
It also addresses how we can get a user to enter a uint64 number - without the q added to it.
You can do the following:
Turn a string into a uint64 - and reverse
Add two uint64's together
Subtract two uint64's
Convert uint64 to hex - and reverse
Convert uint64 to a base number
Find the Mid$ of a number
Plus the usual operators, <, <=, >, >=, <>, =.
A good starting point I think.