Learn Spanish (Latin America): Tengo veinte dólares y él tiene veintiuno. - I have twenty dollars and he has twenty-one.

For numbers from 21 to 29, Spanish combines them into a single word. You drop the final -e from veinte, replace it with an -i-, and add the second number. So veinte and uno become veintiuno.

Why does the sentence use veintiuno instead of veintiún?

You only shorten veintiuno to veintiún when it comes directly before a masculine noun (like if you said veintiún dólares). Because the word dólares isn't repeated at the end of this sentence, veintiuno stands alone and keeps its -o.

Why does él have an accent mark?

The accent mark distinguishes él, which is the pronoun meaning he, from el, which is the word for the. Without the accent mark, it would look like you were saying ...and the has twenty-one.

Why does the verb change from tengo to tiene?

The verb tener (to have) is irregular. For I have, you use tengo. But for he has, the root of the word changes slightly to become tiene.