"Seventy, eighty, ninety"
Translation:Сімдесят, вісімдесят, дев'яносто
Why does it go -десят for the first eight multiples of ten, and then -носто for ninety? Is it a left over archaic ending that somehow didn't get replaced?
According to Wikipedia, it is a leftover from Proto-Indo-European ^^. There is also "сорок" that was borrowed from Greek or Turkish through Old Slavic.
You’re using the Latin letter 'i', not the Cyrillic 'і'. Some Cyrillic and Latin letters look the same (other letters like this are a—а, e — е, ï — ї, o — о, p — р, c — с, y — у, x — х), but on computer they are encoded completely differently and most programs don't allow replacing Cyrillic letters with Latin lookalikes.
You probably use a Russian keyboard layout that doesn't include «і». You'd probably need to install Ukrainian keyboard layout, or use some program like AutoHotkey in Windows to allow you to enter і.