Unit 8.1

# Cardinal numbers: Tens

## Introduction

Cardinal numbers give information about how many people or things there are.

Ten numbers go from 1 to 99.

## Form

Ten numbers have ten as its base. However, the numbers from 1 to 9 are commonly called unities.

They have specific features:

• plain form: number + 0
• specific names from 0 to 20
• from 20 to 99 the numbers follow a pattern to name them: using a hyphen in between the ten number and the unit.
 Unities from 1 to 9 Tens from 11 to 19 Tens from 10 to 90 Tens + unities one eleven ten twenty-one two twelve twenty twenty-two three thirteen thirty twenty-three four fourteen fourty twenty-four five fifteen fifty twenty-five six sixteen sixty twenty-six seven seventeen seventy twenty-seven eight eighteen eighty twenty-eight nine nineteen ninety twenty-nine

NOTE: We normally use the singular form of the numbers when we are naming a concrete figure, while we use the plural form when we are not speaking about a concrete number, but in general terms.

## Example

• 10 (ten)
• 25 (twenty-five)

## Use

Tens numbers are used to measure, count, label things, codes from 1 to 99.

In formal writing it is better to write the number in letters when it is a short figure.

## Exercises

The exercises are not created yet. If you would like to get involve with their creation, be a contributor.

Open TextBooks are collaborative projects, with people from all over the world bringing their skills and interests to join in the compilation and dissemination of knowledge to everyone and everywhere.

## Online Teaching

Become a Books4Languages Online tutor & teacher.