Spanish translation on the difference between the numbers 21 and 31 when written?

Why is 21 so much different in writing than thirty one?



21= veintiuno

31= treinta y uno



Why does the number 21 have an "i" in the middle while 31 has a "y" separating it?



Or is 31 actually written as treintaiuno?Spanish translation on the difference between the numbers 21 and 31 when written?
from 21 to 29 you have to write with the "i" in the middle:

22= veintidos

29= veintinueve

from 31 to 99 you have to write it with "y"

35= treinta y cinco

42= cuarenta y dos

I dont know why, it is just the way it is.

bye
Perhaps because the 20s are still common enough to have merged, like the 10s.



Or because veinte y has two vowel sounds that are close - the a y sounds are easier to distinguish.Spanish translation on the difference between the numbers 21 and 31 when written?
I always thought it was Y also? hmnnn.....Spanish translation on the difference between the numbers 21 and 31 when written?
Because "y" is like saying "and". So, veintiuno is just one word, while treinta y uno is written separately, because is like saying: thirty AND one. This no logic explanation.

I hope helped:)



Veitiuno 21

veintidos 22... etc.

while is: treinta y uno 31

treinta y dos 32... etc.

cuarenta 40

cuarenta y uno 41...

like this.
21= veintiuno

31= treinta y uno

Both ARE correct.





Check out these numbers:

21 veintiuno

22 veintidos

23 veintitres

31 treintaiuno (treinta y uno)

32 treintaidos (treinta y dos)

45 cuarenta y cinco

57 cincuenta y siete

84 ochenta y cuatro



In some you use a contraction, in others you don't.

You can know that with practice and, in some cases, learning the numbers.



You're asking about the reason...

mmmm..

I guess we use them like that because those are the most common number used and are easy to write and to say.



In spanish, nobody says this number like this:

31 = "treinta" "y" "uno" (separately)

We just say "treintaiuno" coz is faster .







[I speak such language]
se veria mal si separamos las palabras con y esa es la unica excepcion treintaiuno se veria mal.
They're both acceptable. One is really a contraction. You could have written veintiuno and veinte y uno also. Or treintiuno.