Cardinal numbers are those used in counting: one, two, three, etc. Ordinal numbers indicate position in a sequence: first, second, third, etc. In this lesson, we’re going to list the first twenty Spanish cardinal numbers. We’ll also list the first ten ordinal numbers, as these are the only “must know” numbers for indicating position in a sequence.

Cardinal Numbers

The number one and its compound forms (21, 31, 41, etc.) have both a masculine and feminine form. The masculine uno is shortened to un when it precedes a masculine singular noun.

Ordinal Numbers

The first ten ordinal numbers in Spanish are adjectives and are used frequently in both speech and writing. Unlike in English, where you must always use an ordinal number to indicate sequence (twenty-first, thirty-fifth, eighty-eighth, etc.), in Spanish you can substitute a cardinal number for any ordinal number greater than “tenth.”

Because primero though décimo are adjectives, they end in “o” when modifying a masculine noun and “a” when modifying a feminine noun. In the case of primero or tercero, drop the “o” when either comes before a masculine singular noun.