I also looked at the numbers 20, 30, 40 etc in Turkish. They don't seem to bear any relation to the number that starts them but in English they do.
English
two > twenty (2, 20)
three > thirty (3, 30)
four > forty (4, 40)
five > fifty (5, 50)
six > sixty (6, 60)
Turkish
iki > yirmi (2, 20)
üç > otuz (3, 30)
dört > kirk (4, 40)
bes > elli (5, 50)
Although the post is almost finished, it may be interesting for you to see the rest of the list that you added:
English
seven >
seventy (7, 70)
eight >
eighty (8, 80)
nine >
ninety (9, 90)
ten > hundred (10, 100) [
ten > tenty (10, 100) could be a variety for non-native speakers but there is no such use in living English !]
This shows, as you have already mentioned, that there exists a relation among the first
nine cardinal numbers and their ten folds.
Turkish
altı >
altmış (6, 60)
yedi >
yetmiş (7, 70)
sekiz >
seksen (8, 80)
dokuz >
doksan (9, 90)
on > yüz (10, 100)
This shows that there
also exists a relationship among the last four
-one digit cardinal numbers and their ten folds in Turkish.
The word "
yüz" is also a unique word being not derived from the word "
on" in Turkish, similar to the corresponding ones in English.
There is a suffix
"-ty" to form the ten folds of the last
eight-
one digit cardinal numbers in English. [The ten fold of the first
one digit cardinal number is the number
ten by definition: one > ten (1, 10).]
In Turkish, there is not an equivalent "
-ty" suffix. There seems as if there is such a suffix for the generation of the ten fold cardinals 60 to 90, but it is not an exact rule because it changes from "-mış/-miş" to "-sen/-san".
It is evident that the etymology can be mysterious for many words in every language.