Number names in English and Spanish

There are two types of numbers in Mathematics: cardinal and ordinal numbers. Here I include a list of their names and a few bits of explanation.

Cardinal numbers

These numbers we use most of the times. They indicate either quantity or magnitude.

In English…

• from zero to twenty, they all have their own name
• from there onwards, the last two figures of a number name will have a hyphen
• over a million, every three additional figures there will be a new name; although sometimes you might see "a thousand million" too

While in Spanish…

• from zero to thirty, they all have their own name
• from there onwards, the last two figures of a number name will be named using the ten and the unit
• over a million, every six additional figures there will be a new name

In both languages it is usual to separate every three figures with a small space, for clarity's sake. Computer users use a non-breaking space symbol to prevent a portion of a number to break into a new line.

Ordinal numbers

Ordinal numbers express position, so they are integers and do not have a zero.

In English, you abbreviate the position writing the number plus the last two letters of its name (^st, ^nd, ^rd, or ^th).

In Spanish, you abbreviate the position writing the number plus a degree symbol (º), and you should also know that in Spanish the names of the positions may change the last 'o' to 'a' to match their noun gender.

Fractions

Fractions are just a combination of the previous two: a cardinal number for the numerator and an ordinal number for the denominator, with a few notes:

In English…

• half and quarter have their own denominator name

While in Spanish…

• the numerator always has a cardinal number as name too
• half and third have their own name
• from fourth to tenth, denominators use the ordinal number name
• other denominators will use the cardinal number name plus the suffix -avo, except for round numbers over a thousand, which use the ordinal number name