Veintiun y veintiuno
 

Hello all,

Can you please explain when I would use veintiun or veintiuno? Thank you!!

Before a masculine noun, use veintiún. Uno is always shortened to un before a masculine noun. This shortened form is called an apocope.
un zapato
veintiún zapatos

Use veintiuno when you're counting, or when no noun is being quantified, just the same as using uno for counting or when there's no noun to modify.
uno, dos, ..., veintiuno, veintidós, etc.
Hoy es el veintiuno. (Today is the twenty-first.)

Use veintiuna before a feminine noun, just as you would say una before a feminine noun. (The apocope is used instead if the feminine word begins with a stressed 'a' sound.)
una corbata
veintiuna corbatas

un águila
veintiún águilas
un hacha
veintiún hachas

Thanks again Rusty
 

Thank you so much Rusty for answering yet another question for me. Being 52 and going back to college is not easy, plus working full time. I truly appreciate your help.

Best Regards
Rebecca

You're so welcome.