The prefix is accepted as either "deka" or "deca", and depending on US/GB Engish, "litre" or "liter", just like calibre and colours.
EDIT -
iago, don't you use the Loonie and Twonie coins as worth $1 and $2 CAD? Also, as you may see in older dollar bills, it's actually a certificate that entitles you to a dollars worth of silver stored in some military base somewhere (Fort Knox, I think?). The older bills said "Silver Certificate", but the newer ones say "Federal Reserve Note".