köken: Inherited from Middle French vingt, from Old French vint, from Latin vīgintī, from Proto-Indo-European *h₁wih₁ḱm̥ti, *dwi(h₁)dḱm̥ti. The Latin -g- was regularly lost in Old French, but was added back to the spelling in Middle French (now placed after the -n- in order to maintain the pronunciation).
köken: жиырма (jiyrma) + -ыншы (-ynşy). Cognate with Azerbaijani iyirminci, Khakas чибіргінӌі (çibìrgìncì), Shor чегирбенчи, Turkish yirminci, Uzbek yigirmanchi, etc. The infix -с- because of the ending vowel -а. If Kazakh had a cardinal form **жиырмы /(d)ʒɨ.jɨr.mɨ/ with an -ы vowel, then the ordinal form would be **жиырмыншы /(d)ʒɨ.jɨr.mɨn.ʃɨ/.
köken: From жыйырма (jıyırma) + -нчы (-ncı). Cognate with Azerbaijani iyirminci, Kazakh жиырмасыншы (jiyrmasynşy), Khakas чибіргінӌі (çibìrgìncì), Shor чегирбенчи, Turkish yirminci, Uzbek yigirmanchi, etc.