While searching around the web, looking for a way to assign a unique value to each string in an Excel sheet, I developed the following formula:

=CODE(GROSS(A1))*(1+LÄNGE(A1)*(RUNDEN(WURZEL(CODE(GROSS(LINKS(A1)))*CODE(GROSS(RECHTS(A1))));0)))

However, this formula will not be unique in certain cases. If you happen to know a good hashing function, made entirely in Excel, feel free to contact me.