Finnish, Estonian, Lappish, Mordve, Tcheremisse, Samoyede, ...
I have just realized that languages related to finnish have a very special way of counting 8 and 9:

1 2 8 9 10
Finnish yksi kaksi kahdeksan yhdeksan kymmenen
Estonian üks kaks kaheksa üheksa kümme
Lappish okta guokta gávcci ovcci logi

It really seems that in these languages, 8 is "10 minus 2" and 9 is "10 minus 1". It also seems that the "10" used there is an external contribution to the language. I wonder if the fin. "-deksan", est. "-eksa", lap. "-vcci" come from an indo-european root, like the word for 10 in hungarian is borrowed from an indo-european source. I found no direct correlation with that and the word for "hand" in these languages.

I wonder if languages of another group count 8 and 9 like that...

Update: Latin 9 is IX, ten minus one.