When we use the word number, we refer to specific numbers:
Here’s the phone number of the firm where she works.
She plays in the local hockey team and wears the number six.
We also use the phrases a number of, numbers of or the number of with a plural verb when we mean ‘many’ or ‘several’:
There are a number of things we need to discuss.
A significant number of people are ill with flu so the performance had to be cancelled.
Large numbers of bees have died because of the cold summer.
I couldn’t believe the number of cars that were parked outside the hall.
Numbers: first, second, third
Numbers such as first, second, third are ordinal numbers. We use them to put things in an order. We most commonly use ordinal numbers as determiners. When we use ordinal numbers as determiners (before nouns), we commonly use other determiners such as articles (a/an, the) and possessives (my, your) in front of them:
This was the fifth science exam that he had failed.
It’s her twenty-first birthday and she’s spending it with friends in Malaysia.
We use the ordinal numbers to refer to dates. We usually write them in abbreviated form and often in superscript (above the line). We usually say the and of when we speak, but we often omit them in writing:
My birthday is 3rd January. (usually spoken as ‘the third of January’)
The museum was opened on 25th June 2008.
What are you doing on the 2nd of May? Do you want to join us at the theatre?
We also use ordinal numbers as nouns:
All three singers in the competition were excellent but I’m voting for the third.
Numbers such as one, five, eleven, two hundred are cardinal numbers. We most commonly use cardinal numbers as determiners (before nouns). When we use them in this way, we can use other determiners such as articles (a/an, the) and possessives (my, your) in front of them. We can use cardinal numbers + of before determiners (one of my friends):
She loves animals and has two dogs, three cats and one rabbit.
My two best friends are Amy and Louise.
Three of his colleagues were sacked yesterday. (sacked = lost their jobs)
We also use cardinal numbers as nouns:
The children arrived in twos and threes.
We normally say a hundred, a thousand, a million. We only say one hundred, one thousand and one million when we want to emphasise the number:
What would you do if you won amillion euros? (preferred to one million euros)
The city is about a hundred kilometres from the capital.
Numbers such as 100, 200, 1,000, etc. do not take a plural -s when we use them as determiners:
There were about two hundred people at the meeting.
Not: There were about two hundreds people …
However, we use the plural forms hundreds, thousands, millions + of + noun to refer to large, non-specific numbers:
It’s happened hundredsof times.
Millionsof people live in poverty.
We often use commas in writing to separate long numbers of a thousand or more into each thousand part: