Unit 8.1

Cardinal numbers: Decimals, Tens and Hundreds


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

Decimals are the smallest of the numbers, being the result of fractions. Ten numbers go from 1 to 99. Hundred numbers go from 100 to 999.


Decimal numbers are the result of a fraction.

  • They normally have a comma or a point between the whole number and the decimals.

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

  • Plain form: number + 0
  • They have 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

The hundred numbers have one hundred as its base.

  • Plain form: number + 00
  • Their name is: how the number in the beginning is called + hundred
  • 100 can be called ‘one hundred’ or ‘a hundred’
  • If there are more numbers after the hundred number,  they need to be mentioned as normal (ten number). Sometimes, we use ‘and’ in between the hundred number and the ten number.
  • From 100 to 999
Hundreds from 100 to 900 Hundreds + Unities Hundreds + Tens
one hundred one hundred and one one hundred and ten
two hundred one hundred and two one hundred and twenty
three hundred one hundred and three one hundred and thirty
four hundred one hundred and four one hundred and forty
five hundred one hundred and five one hundred and fifty
six hundred one hundred and six one hundred and sixty
seven hundred one hundred and seven one hundred and seventy
eight hundred one hundred and eight one hundred and eighty
nine hundred one hundred and nine one hundred and ninety



  • 567/100 = 5,67
  • Five point sixty-seven


  • 10 (ten)
  • 25 (twenty-five)


  • 100 (one hundred)
  • 871 (eight hundred seventy-one)


We normally use the singular form of the numbers  – when we are naming a concrete figure.

We use the plural form when we are not speaking about a concrete number, but in general terms. We don’t even use a whole number for that:

  • Hundreds of + noun (“There were hundreds of adolescents in that party”)

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