Learn the basics of Spanish with this easy-to-understand course Chapter -4

You've already learnt how to refer to a noun using either the definite
or indefinite article.

But what happens if you want to specify a number?
For this, you will need to know your cardinal numbers.
The cardinal numbers one to ten are as follows:
1 - uno
2 - dos
3 - tres
4 - cuatro
5 - cinco
6 - seis
7 - siete
8 - ocho
9 - nueve
10 - diez

If you just look over the previous chapter on the Indefinite Article,
you'll realize that the number one changes from uno to un before a
masculine noun and from uno to una before a feminine noun.

For example:

un niño .......... one boy

una niña ........ one girl

Use uno when counting generically, as in:

one, two, three, four, etc

uno, dos, tres, cuatro, etc

Use un or una when counting specifically, as in:

one banana, one apple, etc

un plátano, una manzana, etc

Cardinal Numbers 11-20
Following on from the last chapter, the cardinal numbers eleven through
to twenty are as follows:
11 – once
12 – doce
13 – trece
14 – catorce
15 – quince
16 – dieciséis
17 – diecisiete
18 – dieciocho
19 – diecinueve
20 – veinte

In Spanish, the numbers 16 through to 19 are actually contractions.
For example, the Spanish for 16 – dieciséis – literally means ten and
six, but joined together, as shown below:

dieciséis = diez y seis

diecisiete = diez y siete

dieciocho = diez y ocho

diecinueve = diez y nueve

Cardinal Numbers 21-99
The cardinal numbers twenty-one to thirty are:
21 – veintiuno
22 – veintidós
23 – veintitrés
24 – veinticuatro
25 – veinticinco
26 – veintiséis
27 – veintisiete
28 – veintiocho
29 – veintinueve
30 – treinta

You'll notice that, like the cardinal numbers 16 to 19, the numbers 21
to 29 are contractions of the Spanish for twenty and one etc:

veintiuno = veinte y uno

veintidós = veinte y dos, etc

Numbers between 40 and 100 are not usually done as contractions but
add y uno ... y dos etc.
40 – cuarenta
50 – cincuenta
60 – sesenta
70 – setenta
80 – ochenta
90 – noventa

Consequently, the Spanish for sixty-two would be sesenta y dos.
Other examples are:
79 ...... setenta y nueve
86 ...... ochenta y seis
93 ...... noventa y tres