Treinta y uno & Treintauno

Question

All numbers from: 16-Dieciseis... to... 29-Veintinueve are written in the same form.

Why is there a change from number 31? Does all numbers from 31 have to be wriiten in form: 31- Treinta y uno 73- Setenta y tres 99- Noventa y nueve

Is there any reason why this change?

Thanks

Only 21 is written veint i uno all the other have a separate Y and the unit number - ian-hill, Nov 16, 2013

example 31 = treinta y uno - ian-hill, Nov 16, 2013

Answer 1

All numbers up to 30 are written as one word. "Y" is placed between tens and units but not between hundreds or thousands and units or tens.

Uno and all numbers ending in uno become un before a masculine noun. Una does not change before a feminine singular noun.

Answer 2

funny thing is, that there is: 101- Ciento uno (NOT as I thought it will be Ciento y uno)

why?

Answer 3

Languages have developed by incorporating many features that include patterns and sometimes mere conveniences that prevent tongue twisters.

For example, the numbers after veinte are actually contractions that avoid some twisting of the tongue. Veintinueve is actually a contraction of veinte y nueve. After treinta that does not happen. There's no problem speaking treinta y uno, and so on. I hope that helps clarify to some degree.

Answer 4

My previous answer really didn't answer your question. As far as I can see the answer to "why" is because these are the rules and have to be learnt by heart. Consider the numbers ciento, mil and un millión.

1) Ciento is shortened to cien before a noun or an adjective but not before another number with the exception of the number mil. Why? because that's the rule.

2) Cien and mil are not preceded by the indefinite article. Note that the plural miles meaning "thousands" is followed by de plus a noun.

3) Un millón (plural millones) must be followed by de. Millón however, is preceded by the indefinte article unlike cien and mil.

These are the rules and one just has to learn them.