99 would be "nioghalvfems" which is the short version of "nioghalvfemsindstyvende".
It's a mix of "halvfemte" which means 4½, "sinde" which means to muliply and "tyve" which is 20. So 90 is actually 4½ times twenty. So when we say 99 we technically say 9 and 4½ times twenty.
Yes, that makes perfect sense. On Mars.

 
				 
 
		 But we still love the Danes.
 But we still love the Danes. 
 
		 But I agree that it's confusing for non-native speakers
 But I agree that it's confusing for non-native speakers  
 
		 
 
		 
 
		 
 
		 
 
		