The numbers ‘twenty’ to ‘ninety’ end in ‘-ty’.
Where does this part come from?

While it’s now a suffix, ‘-ty’ stems from a Proto-Germanic noun meaning “decade, a (group of) ten”.

For example, ‘forty’ comes from *fedwōr tegiwiz, literally “four tens”.

Only Icelandic, Swedish, and Elfdalian have preserved this word as a noun.

Click my new graphic to learn all about ‘-ty’ and its relatives: